남은 건

what’s left

→ 남다
phrase Rare #26,687
what’s left 건 is a contraction of 것은, meaning “the thing that is.” 남은 건 refers to something that remains, while 남는 건 refers to something that will remain or is left over.
KO: 이제 남은 건 집에 가는 것뿐이에요.
EN: Now all that’s left is to go home.

이제 나 한테 남은 건 너 밖에 없어

Now, all I have left is you.

— 박쥐 (2009)