An occupied place is being controlled by an army or group of people that has moved into it.

occupied territory 占领区

She spent two years in occupied Paris (= Paris when it was under foreign control) during the war. 战争期间她在沦陷的巴黎住了两年。

being used by someone; with someone in it

The bathroom at the back of the plane was occupied, so I waited. 飞机尾部的厕所有人使用，所以我等着。

busy or interested

At that time I was fully occupied taking care of my elderly mother. 那段时间我的时间都用来照顾我年迈的母亲了。

All the new toys kept the kids occupied for hours. 这些新玩具让孩子们兴致勃勃地玩了好几个小时。