en_tn/2co/03/06.md

a covenant not of the letter

Here the word "letter" means letters of the alphabet and refers to words that people write down. The phrase alludes to the Old Testament law. Alternate translation: "a covenant not based on commands that men have written" (See: rc://en/ta/man/jit/figs-synecdoche and rc://en/ta/man/jit/figs-explicit)

but of the Spirit

The Holy Spirit is the one who establishes God's covenant with people. Alternate translation: "but a covenant of the Spirit" or "but a covenant based on what the Spirit does" (See: rc://en/ta/man/jit/figs-ellipsis)

the letter kills

Paul speaks of the Old Testament law as a person who kills. Following that law leads to spiritual death. Alternate translation: "the written law leads to death" (See: rc://en/ta/man/jit/figs-personification and rc://en/ta/man/jit/figs-explicit)