「明日」 means tomorrow, referring to the day after today. It's frequently used when making future plans or talking about events that will happen the next day. This is a key word for future scheduling.

「今日(きょう)」の次(つぎ)の日(ひ)を意味(いみ)します。明日(あした)の予定(よてい)や出来事(できごと)を話(はな)すときに使(つか)います。