combination lock (using letters/characters)
Specifically a lock opened by aligning letters or characters, as opposed to a numeric combination lock.
This suitcase has a combination lock with letters.
A numeric combination lock, while 文字合わせ錠 uses letters or characters.
A general dial lock, which may be numeric or alphabetic; 文字合わせ錠 specifies a letter-based mechanism.
Compound of 文字 (moji, 'letter/character'), 合わせ (awase, 'matching/aligning'), and 錠 (jō, 'lock').