a lot 很多,out of somebody,从某人身上拿出来,
所以take a lot out of somebody字面意思就是从某人身上拿出了很多,
这里表示拿了很多精力,所以这句短语表示花了某人很多精力,消耗了某人很多精力,把某人累坏了的意思。
开这个派对把我累成狗了:
Throwing this party took a lot out of me! (throw a party:开派对)
准备高考很累人,耗费了我很多精力:
Preparing for the college entrance examination took a lot out of me!(college entrance examination: 高考)