Tadaima means "I am home" or "I'm back." You say this when you return home, addressing the people inside. It's a common and expected greeting upon entering your residence. It signals your return. For example, when you walk through the door, you'd say, "ただいま！" (I'm home!).

家に帰ってきた時に、中にいる人に言う言葉です。自分の帰宅を伝えます。「ただいま！」