Itte kimasu means "I am leaving" or "I'm off," literally "I will go and come back." You say this when you leave your home or office, addressing those who remain. It implies you'll return. For example, when going to school, you'd say, "学校へ行ってきます！" (I'm off to school!).

家や職場を出る時に、残る人に向けて言う言葉です。また戻ることを伝えます。「学校へ行ってきます！」