What does Acts 10:19 mean?

Immediately before Jesus ascended to heaven, He told the disciples, "But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth" (Acts 1:8). They received the Holy Spirit about ten days later, on the day of Pentecost (Acts 2:1–4). Immediately after and for some time, Peter and the others shared the gospel in Jerusalem, establishing the new church (Acts 2:5—6:15). After Stephen was murdered (Acts 7:54–60), the Sanhedrin started persecuting the Jesus-followers in earnest (Acts 8:1–3) driving them out of Jerusalem. The Jesus-followers spread into Judea and Samaria, taking the gospel with them (Acts 8:4–40).

Philip has already shared Jesus' message with an Ethiopian official (Acts 8:26–40). Historically, Ethiopia has one of the oldest and longest-standing churches. But now Jesus' last commission, to take the news of salvation through His death and resurrection to "the end of the earth," is coming. Peter had a vision about how God is removing the kosher food laws (Acts 10:9–16). While he is still trying to figure out the deeper meaning of the vision, the Holy Spirit directs his attention to three visitors—at least one of whom is a Gentile and, therefore, himself unclean. If God can revoke dietary restrictions, He can certainly welcome Gentiles into His kingdom.