The following is an annotated version of the fairy tale. I recommend reading the entire story before exploring the annotations, especially if you have not read the tale recently.
ONCE on a time there was a man who, as he was walking along, found a pea, and said to himself, "I will plant this pea and when the pea-stalk grows up it will bear many peas, and so I shall be able one day to lade ships with them, perhaps even the twelve ships of the King. With that thought in his head he got up and went to find the King and have an audience with him. So he presented himself before him and asked him for his twelve ships, that he might lade them—with his one pea! which he had in his shoe.
When the King heard the words of this young hero, he said to him, "If it please you I have a daughter whom I think worthy of you."
But I forgot to tell you that this man, as he was going to see the King, met with a dragon, who said to him, "Whither away?"
"To seek my fortune," he replied.
"Your fortune is made if you prove able to answer me ten questions," answered the dragon, "but otherwise you are lost. And if on the other hand you do answer the ten questions, you will be presented with that palace that you see there, as it is, with all its belongings, gardens and estates, and I shall burst asunder as soon as you answer me all my questions."
Let us leave the dragon, then, who had made this bargain with Penteclemas (for so the young man was called), and let us come to speak of the King who desires him for a son-in-law.
Now poor Penteclemas thought if he were to say "No!" the King would not believe his word and would not let him have the ships. So he thought he had better say "Yes!" and see how things turned out. When he had given his consent, the King, in order to assure himself whether he was rich or poor, gave orders to a servant to put ragged sheets and a torn coverlid on his bed, for Penteclemas to pass the night on. And when night fell he said to him, "Go to your chamber, for it is time to sleep." The King told the servant to watch all night long to see whether he went to sleep or not.
"For," said he, "if he sleep, it is a sign he is poor; but if he do not sleep it shows he has been accustomed to new bed-clothes and cannot sleep on rags." In the morning the servant tells him that Penteclemas was restless all the night and never closed his eyes. Then the King orders him on the following night to lay the bed properly and with due regard to comfort. And not to make a long tale of it, in the good bed our young hero sleeps as sound as sound could be, because he had no fear of losing his pea in this bed. So the King was satisfied that he was a youth of good birth, and married him to his daughter.
But the reason why he had not slept the first night was not because of the ragged bed-clothes, but only because he was afraid of losing the pea and not being able to find it.
After a time he began to think of what he should say to the dragon, since the time was drawing near—forty days' grace having been fixed.
When the wedding had taken place about three days, our young hero wished to leave home, and the Princess desired to accompany him. Accordingly a considerable retinue followed in her train, and her husband, Penteclemas, went to the dragon's castle in order to learn his fate, and see what would befall him. He went on in front, and a short distance behind followed his wife with her train of attendants. Penteclemas said to them, "If the Princess asks whose are these estates, mind you tell her they belong to Penteclemas. This can do you no harm." And as luck would have it the Princess actually did ask once or twice about the estates, and when she heard they belonged to her husband she was very much pleased. But the unfortunate Penteclemas kept thinking over the words of the dragon, and what sort of questions he would ask him; for the time allowed was drawing to an end.
When they arrived at the dragon's castle, he and his wife went up the steps, and the rest of the company took their leave. Penteclemas was very thoughtful. His wife said to him, "What ails you?"
"Nothing," said he, for what should he answer her, and how was he to tell her what was going to happen, when the time for the dragon's approach drew near? At last an old woman from the neighbourhood saw the wife of Penteclemas sorrowful.
"What ails you?" she asked.
She answered, "Seeing my husband sad and thoughtful, I am sad as well."
Then the old woman goes to Penteclemas and puts the same question to him. What had he to hope from the old woman? So he hid his thoughts from her, till at last she got impatient, and then he told her. The old woman consoled him, saying, that when the dragon came she would answer the questions he put, and that he was never to mind the dragon at all, but only to comfort the Princess who was so sorrowful.
When the dragon came he called out, "Are you there?"
"Glad to see you!" shouts the old woman, pretending to be Penteclemas. Then they close the doors and the dragon and the old woman are shut up together in the castle.
The dragon cries, "What does one stand for?"
"One stands for God!" cries the old woman
Dragon: "What does two stand for?"
Old Woman: "Even-handed justice!"
Dragon: "What does three stand for?"
Old Woman: "The three legs of the trivet that they put the pot on."
Dragon: "What does four stand for?"
Old Woman: "The four teats of the cow."
Dragon: "What does five stand for?"
Old Woman: "The five fingers of our hands."
Dragon: "What does six stand for?"
Old Woman: "The six stars in the constellation Pleiades."
Dragon: "What does seven stand for?"
Old Woman: "A dance of seven damsels."
Dragon: "What does eight stand for?"
Old Woman: "The eight tentacles of the eight-footed octopus."
Dragon: "What does nine stand for?"
Old Woman: "Nine months your mother bare you."
Dragon: "What does ten stand for?"
Old Woman: "Why that's your own number. Burst, dragon, burst!"
So the dragon burst, and Penteclemas inherited the castle and all its belongings, and lived happily with the Princess, and they loaded the old woman with money.
Source:
Geldart, Edmund Martin. Folk-Lore of Modern Greece: The Tales of the People. London: W. Swan Sonnenschein and Company, 1884.