Vocabulary
남
other people, others
Meaning
남 : other people, others. Refers to someone outside oneself or one's close circle; 남이 includes the subject marker.
Why this form?
다른 사람 — “another person” is neutral; 남 foregrounds self versus others.
Forms not to confuse
다른 사람
다른 사람이 왔어요. — Someone else came.
Examples
남이 자는 걸 지켜보는 사람이 어디 있어요??! — What kind of person watches others sleep?!
남의 물건을 가져가면 안 돼요. — You mustn't take other people's belongings.