To change places; to relieve one another — to swap positions or to take turns replacing one another (intransitive).
昼と夜の担当が入り替わるので、勤務表を確認してください。
Day and night shifts will change places, so please check the duty roster.
席が入り替わって、隣の人と顔ぶれが変わった。
Seats were swapped, and the people sitting next to me changed.
選手が順に入り替わってコートに入る。
Players take turns and enter the court.