When to use older sister in Korean
Korean: 누나[ nu-na ]

When to use it
누나 means “older sister.” Boys and men use this word to talk to or talk about their older sister. It can also be used for an older girl or woman they are close to, but for beginners, think of it as “older sister.”
Example sentences
집에서 누나랑 밥을 먹어요.
I eat with my older sister at home.
우리 누나는 학교에 가요.
My older sister goes to school.
누나, 이 책 좀 봐 주세요.
Older sister, please look at this book.
주말에 누나와 공원에 갔어요.
I went to the park with my older sister on the weekend.
누나가 가게에서 우유를 샀어요.
My older sister bought milk at the store.
내일 누나랑 부산에 가요.
I’m going to Busan with my older sister tomorrow.