The King explains how his arena works. There is a Lion and a Woman Each behind a different door. You put a man in, and he chooses a door. He either gets eaten or marries the woman on the spot.
The Princess and her boyfriend are found together and the king doesn't like it. He decides to use him in his arena the next day. The princess is not happy with her father for making this choice, but she knows she can't do anything.
She is trying to figure out what door to pick (Internal Conflict)
The king locks up the boy for trial later the next day. While the boy is locked up, he goes and finds the biggest, most brutal tiger to put in the arena with the boy. He is a very brutal king.
The king puts the boy in the arena for trial. He stands there thinking about what door to pick as the crowd gathers round, wondering whether he will get devoured or married.
He then looks up into the arena audience and makes eye contact with the princess. She tells him which door to choose. She moved her arm slightly to right and acted like she was stretching.
He then walks up to the right door and opens it. The story does not tell you what was behind that door though, that is for you to decide . . .