What does Acts 11:7 mean?

To this point, the church in Jerusalem is made of Jews and proselytes to the Jewish religion. The "Hellenists" mentioned in Acts 6:1 are not ethnically Greek; they're Jews who lived outside of the traditionally Jewish regions of Judea and Galilee. Hellenized Jews were more familiar with the Greek language and culture. Many of the people who heard Peter preach on the day of Pentecost had similar backgrounds (Acts 2:7–11).

The "uncircumcised" with whom Peter ate in Caesarea Maritima, however, were Gentiles. Their host was Cornelius, "a centurion of what was known as the Italian Cohort" (Acts 10:1). That means Cornelius and at least some of his soldiers, friends, and family are Roman. Jews do not eat with Gentiles. Although Jesus had told the disciples they would be His witnesses "to the end of the earth" (Acts 1:8), they didn't really understand that meant Gentiles would be part of the church.

So, when Peter was praying on a rooftop, waiting for a meal, God gave him a vision of a sheet lowering from heaven containing all types of animals, some clean and some very much against the Mosaic law regarding food. Peter is explaining to the church leadership that God told him to eat these unclean animals. After the vision, when three messengers came to take Peter to Cornelius, Peter realized the vision was about the food, but it was also about people with whom he ate the food. Both the food laws and the laws against associating with Gentiles are lifted; it's hard to say which revelation is hardest for people like Peter to accept (Acts 10:9–23).