a reply (to a letter, email, fax, etc.); sending an answer or response, typically in writing or electronically.
いただいたメールにすぐに返信しました。
I replied to the email I received right away.
お問い合わせには24時間以内に返信いたします。
We will reply to inquiries within 24 hours.
返信をもらったら、次の手続きを進めます。
Once we receive a reply, we'll proceed with the next steps.