What does あっ mean?
あっ is a Japanese interjection meaning “ah; oh” in English. It can also be translated as “hey!” depending on context. It is written as あっ in hiragana, and a in romaji. This word is part of JLPT N4 vocabulary.
Example sentence
あっ、いけない！忘れるところだった！
Oh, no! I almost forgot!