Paul

Your language may have a particular way of introducing the author of a letter. Alternate translation: "I, Paul"

Sosthenes our brother

This indicates that both Paul and the Corinthians knew Sosthenes. Alternate translation: "Sosthenes, the brother you and I know" (See: rc://en/ta/man/translate/translate-names and rc://en/ta/man/translate/figs-explicit)