partition; division; separation; segmenting; splitting
「分割」 has another reading with different meanings.
rate; ratio; percentage
部屋を分割して、二つの部屋にしました。
I divided the room and made it into two rooms.
画面を三つに分割して使っています。
I'm using the screen divided into three parts.
ケーキを八等分に分割しましょう。
Let's divide the cake into eight equal parts.