The king is asking the oracle if he "will ever have a son". The oracle is telling that he "will not have a son but will have a grandson, and his grandson will kill him".
After he had heard what the oracle had said he wanted to kill his daughter so that she will never have a son but he was afraid that he will be punished by the gods. So he just threw her into the sea where there was a prison so she could never have a son.
The king's daughter had a son with Zeus. After he had heard this news he had them sent away in a box into the ocean so they could die. But they didn't die, instead they ended up on a island where they were found by a fisherman.
Perseus was on a mission to bring back Medusa head. Athena and Hermes gave Perseus the things he needed to defeat Medusa. Hermes gave him a shield and Athena gave him a sword.
Perseus found the three Gray women. They knew the way to the Gordon. They refused to tell him, so Perseus took their one eye that they all shared and said " I will throw your eye into the sea if you don't tell me where the Gordon lay.
Perseus went to the island of the Gordon. He saw that the Gordon were all sleeping . So Perseus had flew down where they lay and cut off Medusa head and flew away the sisters of the Medusa woke up and saw the head of Medusa and were angry when they saw what someone had done to one of their kind .