noun
written apology; written statement of regret
A formal written reflection on one's mistake, often required in school or workplace settings.
遅刻したので反省文を書かされた。
I was made to write a written apology because I was late.
先生に反省文を提出した。
I submitted a written statement of regret to the teacher.
Compound of 反省 (reflection, self-examination) and 文 (writing, sentence).