What does Luke 24:49 mean?
Luke is condensing several weeks in this passage. Jesus meets with the disciples in Jerusalem the night of His resurrection (Luke 24:36). He also meets with them in that same room, after another eight days (John 20:24–26). Later, He finds seven of the disciples fishing on the Sea of Galilee (John 21). At some point, He meets with five hundred men. He also meets with His half-brother James (1 Corinthians 15:6–7).Near the end of His stay on earth, Jesus and the larger group of disciples return to Jerusalem. We don't know why; there's no required festival for another ten days. There's no indication that the Pharisees, scribes, chief priests, or elders see Him, although they must hear the accounts from others.
Jesus tells them to stay in the area. It is in Jerusalem that they will receive the baptism of the Holy Spirit: a permanent connection with God that seals their salvation (Acts 1:4–5; 2 Corinthians 1:22). They will also receive power: to speak in foreign languages they don't know, heal the sick and injured, and receive insight into hidden things (Acts 2:6; 5:3–4, 12–16).
Now, Jesus leads them to Bethany on the Mount of Olives and gives them one last blessing before ascending into heaven (Luke 24:50–53; Acts 1:6–11). They still don't know what the plan is. But they have faith that Jesus' promises are true, which is enough.
Although Jesus doesn't mention the Holy Spirit by name, this is one of many passages that refer to all three Persons of the Trinity.