Jesus took the Twelve to one side. He told them, "We are going up to Jerusalem. Everything that the prophets wrote about the Son of Man will come true.
References for Luke 18:31
He will be handed over to people who are not Jews. They will make fun of him. They will laugh at him and spit on him. They will whip him and kill him.
On the third day, he will rise from the dead!"
The disciples did not understand any of this. Its meaning was hidden from them. So they didn't know what Jesus was talking about.