What does Acts 22:25 mean?

If the tribune had asked Paul why the mob outside the temple wanted him dead, it is reasonable to assume that Paul would have explained. He likely would have said that he believes Jesus of Nazareth is the Jewish Messiah and died and rose again to offer forgiveness of sins and reconciliation with God for the Jews and the Gentiles. The Jews, Paul would likely have said, don't like the idea of sharing their position of God's chosen people with others from around the world. So, when they realized that Paul associated freely with Gentiles, they responded with violence.

The tribune didn't ask. Instead, he allowed Paul to address his accusers (Acts 21:27–40), but after Paul's speech (Acts 22:1–21) he still didn't apprehend what was happening. This is understandable. The tribune's assignment is probably only for a year. He mostly likely speaks Greek and the dialect of his home region, but not Aramaic—which Paul uses to give his defense before the Jews. But it is the tribune's job to uncover why the people under his supervision are threatening to riot, so he will use the Roman way of extracting information: torture.

The centurion is a commander of about 100 soldiers. He is a career military officer who, nevertheless, must take the orders of the tribune who is serving in the army for career-broadening before a lifetime of politics. But the centurion is experienced, and when Paul mentions that he's a Roman citizen, the officer knows they're in trouble. A Roman citizen may not be bound, which Paul currently is, and may not be scourged without being condemned by a public hearing. The centurion brings the matter to the tribune who investigates—but does not release—their hapless prisoner.

The English Standard Version says, "they stretched him out for the whips" and has a footnote with the alternate, "when they had tied him up with leather strips." The New American Standard Bible says, "they stretched him out with straps." The New King James reads, "they bound him with thongs." It is true that the soldiers mean to flog Paul, but the verse seems to be describing the manner in which Paul is stretched out, not the whips that will be coming his way.