Same form after any noun; ALWAYS followed by a negative: 밖에 없다, 밖에 안/못 …
only, nothing but (with a negative)
Example
지금 제 지갑에 천 원밖에 없어요.
I only have 1,000 won in my wallet right now.
Word parts
Literally 'outside of' (밖 'outside' + 에): nothing beyond this amount.
Good to know
Unlike 만, 밖에 must be followed by a negative: 하나밖에 없어요, never 하나밖에 있어요.