The Greek gramma refers to a letter (of the alphabet), a piece of writing, a document, or the written text. In the plural it can mean 'letters' (written characters), 'writings' (sacred Scriptures), or education ('letters/literacy').
Paul's use of gramma in contrast to pneuma (spirit) is one of his most significant theological distinctions. 'The letter (gramma) kills, but the Spirit gives life' (2 Corinthians 3:6) — not a dismissal of Scripture, but a contrast between legalistic compliance with written code and Spirit-empowered covenant relationship. In Romans 2:27-29, circumcision of the heart 'by the Spirit, not by the written code' is true circumcision. Yet the same Paul says the sacred writings (grammata) are able 'to make you wise for salvation through faith in Christ Jesus' (2 Timothy 3:15). The gramma that kills is the law wielded as a merit system; the grammata that saves are the Scriptures received in faith as God's word.