"우리는 생각이 제각각 입니다."
Translation:We each have our own thoughts.
제각각 can be both noun and adverb.
제각각 (noun) = state of being original/distinctive (not the same as anything or anyone else)
제각각 (adv) = exclusively, distinctively
In the given example, with the use of 이다 (be) it is safe to assume that 제각각 is used as a noun. So,
우리는 생각이 제각각 입니다 -
Lit. "Our thoughts are not the same as anyone else's"
In other words,
"As individuals, we all think differently" or "We each have our own ideas/thoughts"