What does Acts 11:12 mean?

By this time, the Jewish leaders of the church in Jerusalem must be on the edge of their seats. Ultra-legalistic Jesus-followers have charged Peter with the "crime" of eating with Gentiles (Acts 11:2). At that point in history, the church may follow Jesus, but they were still Jews who worshipped a Jewish Messiah and, so far as they know, the Mosaic law still stands in full effect.

Peter has told them how God sent him a vision when he was praying on the rooftop of a tanner named Simon in Joppa. The vision explained that the laws about what foods are allowed has been rescinded. The moment the vision ended, three men from Caesarea Maritima, thirty-five miles north, arrived and requested Peter return with them to the home of a centurion named Cornelius. It's possible Peter worried Jesus' prophecy about Peter's crucifixion is about to come true (John 21:18–19). But the Holy Spirit tells Peter to go without quibbling or delaying (Acts 10:9–23).

Jewish Jesus-followers from Joppa came with Peter and witnessed what happened (Acts 10:45). Fortunately, they came to Jerusalem, as well. In Jewish law, two witnesses are required for testimony to be considered proved; Peter didn't seem to come with anyone from Jerusalem in this trip. Having the six from Joppa with him gives credibility to his story.