What does Acts 28:16 mean?

Over two years prior, Paul had returned to Jerusalem from his third missionary journey. He had accompanied several Gentiles from churches around the Aegean Sea: those who had brought support for the church in Jerusalem. While visiting the temple one day, non-Christian Jews from the same area wrongfully accused him of bringing one of his Gentile friends into the temple. They started a riot and incited a mob to drag Paul from the temple and beat him. The Roman tribune, the army officer assigned to the nearby Antonia Fortress, sent his soldiers to rescue Paul. After investigating for several days, the tribune realized two things: he would never understand why the Jews decided to beat Paul, and he would never be able to protect Paul from the murderous Sanhedrin. He sent Paul to the governor in Caesarea Maritima (Acts 21:27—23:35).

Governor Felix quickly realized that Paul was innocent but also understood that if he let him go free the Sanhedrin would cause problems. He kept Paul under house arrest in Caesarea for two years until he was recalled to Rome for cruelty (Acts 24). His successor, Governor Festus, also wanted to placate the Jewish leaders but didn't realize his efforts made Paul vulnerable to assassination. Paul settled the issue by appealing his case to Caesar, which was his right as a Roman citizen (Acts 25:1–12).

After a harrowing sea voyage (Acts 27), Paul has finally reached Rome, along with Aristarchus, who is also a prisoner (Colossians 4:10), and Luke. Because Paul is a Roman citizen and Festus sent no real charges against him, he settles under house arrest in an apartment he pays for himself. He does have a constant guard, possibly chained to him. But he is allowed to meet with whomever he wishes. During his two-year stay, he tries to bring the Jews in Rome to faith in Christ, he meets with several Gentiles, and he writes Ephesians, Philippians, Colossians, and Philemon. Presumably at the same time, Luke writes the book of Acts.