What does Acts 9:23 mean?

The timeline here can be difficult to follow. Right after Saul becomes a Jesus-follower, he preaches in Damascus. He also goes to Arabia, which is quite close to Damascus, and returns again to Damascus. This time is described as lasting three years in Galatians 1:17–18. It seems that the Jewish leadership plotted against Paul at some point in Damascus and then later the governor under King Aretas apparently threatens to kill him, or perhaps the Jewish leaders plotted with the help of the governor. In either case, Saul escapes out the wall in a basket (Acts 9:23–25; 2 Corinthians 11:32–33). Finally, he makes his way to Jerusalem (Acts 9:26; Galatians 1:18).

It's not clear if Acts 9:23–25 describes Saul's first or second escape from Damascus. Luke is usually more specific in his timelines, but only when he has exact information to work with or he is with Saul personally. It's possible Saul is forced out of Damascus only once, and both the Jews and the Damascus governor want him gone.

"Jews" is the Greek word Ioudaioi. It does not refer to Jewish citizens or laymen but to Jewish religious leaders and those who follow them. This isn't the first plot Saul will have to survive in his work for God. In Corinth, the Jewish leaders try to charge him before the proconsul; the proconsul dismisses the case, saying it is a matter of religion, not civil unrest (Acts 18:12–17). When Saul is trying to get back to Jerusalem from Macedonia, he must change his travel plans because of a plot (Acts 20:3). And after his arrest in Jerusalem, some Jews (probably from modern-day Asia Minor) plot with the Sanhedrin to murder Saul on his way to the governor's estate in Caesarea. Fortunately, Saul's nephew overhears and tells the centurion who takes precautions (Acts 23:12–35).