What does Acts 9:7 mean?

Saul has been stopped outside of Damascus by a bright light and the voice of Jesus asking why he is persecuting Jesus' followers. Saul's traveling companions see the light and hear a noise, but they can't understand the words (Acts 22:9). This is not unlike the time Jesus asked God the Father to glorify His name and God responded. Some people heard God the Father's words clearly while others heard only thunder (John 12:28–29). Or the time only Daniel could see a vision, although the men around him fled in fear (Daniel 10:4–7). Only those God chooses can hear Him.

This is drastically different from where Saul thought he would be. Not long ago, he stood proudly, watching over the coats of the men who stoned Stephen, a deacon of the church, to death (Acts 7:58). Then he chased the Jesus-followers in Jerusalem, arrested them, and brought them to trial (Acts 8:1–3). When the Jesus-followers fled, he traveled 133 miles from Jerusalem to Damascus to continue terrorizing the new church (Acts 9:1–2).

Now, he is knocked to the ground. The man his mentors crucified is speaking to him from the midst of the light of the glory of heaven. As Jesus warned His disciples, Saul thought he was doing God's will by persecuting these upstarts (see John 16:2). He was wrong.

There's some discrepancy between Luke's account here, based on Saul's testimony, and Saul's later testimony to King Agrippa. In Acts 26:14, Saul says, "And when we had all fallen to the ground…" Did the other men stand (Acts 9:7) or fall (Acts 26:14)? "Stand" is from the Greek root word histēmi and, like the English, can either mean "balance upright on one's feet" or "to remain fixed in a situation." So, one option is they fell to the ground and their inability to speak remained through the event. Another is that the men fell and then stood again while Saul stayed on the ground.