해야 할 일은

as for what needs to be done

→ 하다
phrase Rare #26,022
as for what needs to be done A topic-marked phrase meaning “as for the thing(s) one has to do.” 해야 할 일 means “the thing(s) one has to do,” and 은 marks it as the topic.
KO: 오늘 해야 할 일은 모두 끝냈어요.
EN: I finished everything I had to do today.

해야 할 일은 해야지.

You've got to do what needs to be done.

— 씨너스: 죄인들 (2025)

내가 해야 할 일은 알겠어요

I know what I need to do.

— 반지의 제왕: 반지 원정대 (2001)

제가 해야 할 일은 거기까지 였죠

That was all I had to do, right?

— 이중 배상 (1944)