여기 있는 걸

that someone or something is here

→ 여기
phrase Rare #24,711
that someone or something is here 걸 is a common contraction of 것을, making the clause an object. The person or thing that is here is often understood from context.
KO: 네가 여기 있는 걸 아무도 몰라.
EN: No one knows that you're here.

캐서린은 여기 있는 걸 좋아해요,

Catherine likes being here.

— 잉글리쉬 페이션트 (1996)

여기 있는 걸 어떻게 알아?

How do you know it's here?

— 로렌스 애니웨이 (2012)