What does Acts 18:3 mean?

Paul is in Corinth; he'd left Silas and Timothy in Berea. Although he had told his escort from Berea to Athens to send the two to him as quickly as possible (Acts 17:15), he seems to change his mind. He is worried about the harried church in Thessalonica and sends Timothy to check on them (1 Thessalonians 3:6); it's not clear if Silas went with Timothy or stayed in Berea. They don't rejoin Paul until he is well settled into a routine (Acts 18:5).

Fortunately, Paul meets a couple, Aquila and Priscilla, who share his trade of tentmaking. He joins them during the week and spends each Sabbath in the synagogue, trying to convince the Jews and God-fearing Gentiles that Jesus is the Messiah (Acts 18:4).

Paul's choice to work and preach has several different facets. The Jewish school founder Hillel believed a rabbi or scribe should not make money from teaching the Torah. Paul firmly believes otherwise (1 Timothy 5:17–18). But the church in Corinth is somewhat fragile. To keep their attention on his message, he does not ask them to support him (1 Corinthians 9:4, 6–15), even though they do provide support for the church in Jerusalem (1 Corinthians 16:1–3). This contrasts with the church in Philippi which provides Paul support even when he isn't with them (Philippians 4:15).

Paul's experience in Corinth has given us the term "tentmaking;" this means to work full-time at a secular job in order to fund one's ministry work. It usually refers to missionaries who take a job in their host country, such as teaching a language. The job allows them to support themselves without burdening those they serve or sponsors back home, and to get to know the people they are trying to reach in a non-threatening environment.