What does Acts 2:11 mean?
Luke is finishing up his list of groups who first heard the gospel from Jesus' followers. Jesus ascended into a heaven a few days before (Acts 1:9). The Holy Spirit has come down upon the disciples (Acts 2:1–4). Now, a crowd who has come from all over the Roman Empire and beyond is listening to the Jesus-followers speak in their own native dialects.A "proselyte" is a Gentile who has fully converted to Judaism (Exodus 12:48). They perform a baptismal rite of purification and offer a sacrifice. The men are also circumcised. Those who didn't follow Judaism to that extent are sometimes called "God-fearer" (Acts 10:2) or "worshiper of God" (Acts 16:14; 18:7). Ruth may be considered a proselyte (Ruth 1:16–17).
Crete is an island south of the Aegean Sea. Arabia, here, most likely means Nabatea which encompasses the western part of modern-day Jordan and the southern part of modern-day Syria. It's unclear why Luke has singled these two areas apart. Cretans are known for being uncivilized (Titus 1:12) and Arabians for being nomadic; it may be because neither represent the ideal Roman citizen.
What Cretans and Arabians do have in common, as well as the others mentioned in Acts 2:9–10, is that they hear Jesus' disciples speaking in their own "tongue." This is not a heavenly prayer language only understood by God. These are actual languages used by local cultures in addition to the more universal Greek and Aramaic. God is starting His church. He is inviting those who already follow Him through Judaism to accept Jesus as their Messiah—their Savior (Acts 2:36–41). And He's doing it using language that they understand best.