「開ける」(akeru) means to open something, such as a door, window, or box. It is a transitive verb, which means the action is performed directly on an object. Remember to distinguish it from the intransitive verb "開く" (aku). For example: ドアを開ける。(Doa o akeru.) = To open the door.

ドアや窓などを「開いた状態」にすることです。他動詞です。例：窓を開ける。