「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(まど)などを「開(あ)いた状態(じょうたい)」にすることです。他動詞(たどうし)です。例(れい)：窓(まど)を開(あ)ける。