What does Acts 22:8 mean?

This verse is a retelling of Acts 9:5. The Roman army tribune stationed in Jerusalem wants to know why a mob of Jews who had been completely peaceful moments before suddenly dragged Paul out of the temple and beat him. The tribune allows Paul to speak to the crowd in hopes he'll reveal something useful (Acts 21:37–40).

Some attacked Paul because they thought he had brought a Gentile into the temple. Others had no idea why they were attacking Paul—other than their friends were, so there must be a reason (Acts 21:27–30, 33–34). Paul hadn't brought a Gentile in the temple, but he had walked through the city with one. In giving his defense, he starts by explaining that he grew up under the tutelage of Gamaliel, one of the most famous Pharisee rabbis, then describes how he came to follow Jesus of Nazareth.

At this point in the story, Paul was headed to Damascus to hunt Jewish Christians and bring them back to trial in Jerusalem (Acts 9:1–2; 22:4–5). His arrival was interrupted by a great light and a voice asking, "Saul, Saul, why are you persecuting me?" (Acts 9:3–4; 22:6–7)—Saul is Paul's name in Aramaic or Hebrew (Acts 13:9). As the story progressed, Paul learned Jesus was speaking to him. Jesus told him to enter Damascus and wait for Ananias. Ananias found him and helped him turn to Christ (Acts 9:6–19). When Paul later returned to Jerusalem, his former allies turned against him. In response, Jesus told him he will be His witness to the Gentiles (Acts 22:9–21).