 Well, they had no idea of what Jesus was talking about. He was alluding to the fact that he had to have the cup of wrath poured out upon him, a baptism of torment and pain upon the cross, because he just mentioned that that's why he's going to Jerusalem. He shall be betrayed by the chief priests and the scribes, and they'll condemn him to death and deliver him out to Gentiles to be mocked and scourged and crucified. On the third day he shall rise.