What does Acts 8:40 mean?

Just before Jesus ascended into heaven, He told the disciples, "But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth" (Acts 1:8). Philip fulfills this mandate. He started his ministry in Jerusalem, when he was selected as one of the first deacons (Acts 6:5). From there, he went north and saw many Samaritans come to Christ (Acts 8:4–8). The Holy Spirit then told him to travel south, back into Judea, where he met an Ethiopian court official who accepted Christ (Acts 8:26–39).

Now, the Holy Spirit takes Philip to Azotus, known today and in the Old Testament as Ashdod. This is the city the Philistines took the ark of the covenant to after they captured it in a battle in the time of Samuel, before Saul was king. It's also the city where they put the ark with their statue of their god Dagon. One morning, the people awoke to see Dagon on its face in front of the ark; the next morning, Dagon had again fallen, but his head and hands were cut off (1 Samuel 5:1–5).

From Ashdod, Philip makes his way to Caesarea Maritima, about 58 miles north. He most likely travels through Lydda, where Peter was when other Jesus-followers called him to nearby Joppa to heal the devout Jesus-follower Dorcas (Acts 9:36–42). Philip likely also passed through Joppa, where Peter was when he was called on to go to Caesarea and meet the Gentile centurion Cornelius. It was in this situation with Cornelius that Peter realized that Gentiles can follow Christ, as well (Acts 10). Although we don't know the exact chronology of Philip's movements through Judea, it's possible he started the church in Lydda.

Philip's travels started with the persecution of the church led by a young, Pharisee-trained Jew named Saul. Saul terrorized the Jesus-followers in Jerusalem so badly they fled to Judea and Samaria (Acts 8:1–4). Eventually, Saul will expand his scope and go far north to Damascus where he will meet Jesus and a man named Ananias who will help him realize the man he hates is the promised Messiah of the Jews (Acts 9:1–19).