それをやって

do that

→ 其れ
phrase Rare #26,221
do that それを means “that” as the object, and やって is the te-form of やる (“do”). It can be a request or connect to what happens next.
JA: それをやってから、帰ります。
EN: I’ll go home after doing that.

ぜひそれをやってみなさい。

By all means, give it a try.

それをやってしまったらすぐ助けてあげよう。

If you go ahead and do that, I’ll help you right away.

それをやって後悔してる?

Do you regret doing that?

それをやってしまうまでここを出てはならん。

You must not leave here until you have done it.