en_tn/act/15/41.md

he went

The previous sentence implies that Silas was with Paul. Alternate translation: "they went" or "Paul and Silas went" or "Paul took Silas and went" (See: rc://en/ta/man/jit/figs-explicit)

went through Syria and Cilicia

These are provinces or areas in Asia Minor, near the island of Cyprus.

strengthening the churches

Encouraging the believers in the churches is spoken of as though Paul and Silas were making the believers physically stronger. The word "churches" refers to the groups of believers in Syria and Cilicia. Alternate translation: "encouraging the believers in the churches" or "helping the community of believers to depend even more in Jesus" (See: rc://en/ta/man/jit/figs-metaphor and rc://en/ta/man/jit/figs-metonymy)