Konnichiwa means "Hello" or "Good afternoon." This is a general greeting used during the daytime, usually from late morning until early evening. It's versatile and can be used in most situations, formal or informal. For instance, you can say "こんにちは" when entering a shop.

昼間(ひるま)（午前中(ごぜんちゅう)から夕方(ゆうがた)まで）に使う、一般的(いっぱんてき)な挨拶(あいさつ)です。誰(だれ)にでも使えます。「こんにちは！」