Matthew 17:1-3

Three disciples see how great Jesus is

1 Six days after that, Jesus asked Peter and the two brothers, James and John, to go with him. Jesus led them up a high mountain by themselves. 2 Peter, James and John saw Jesus change in front of them. He became different to look at. His face was bright like the sun. His clothes became very white and they shone. 3 Then Moses and Elijah appeared in front of the three disciples. They were talking with Jesus.

17:3Moses had lived a long time ago. He was a leader of God's people. He brought them out of Egypt. He died about 1400 years before Jesus was born. We can read about Moses in Exodus.
17:3Elijah was a prophet of God. He lived about 850 years before Jesus was born. He did not die. God took him up alive to heaven. We can read about him in 1 Kings.