When to use nephew or niece in Korean
Korean: 조카[ jo-ka ]

When to use it
조카 means your brother’s or sister’s child. In English, this is a nephew for a boy or a niece for a girl. You can use this word when talking about family, visits, or gifts for a child in your family.
Example sentences
제 조카는 다섯 살이에요.
My nephew/niece is five years old.
조카가 우리 집에 놀러 왔어요.
My nephew/niece came to my house to visit.
조카는 오늘 학교에 갔어요.
My nephew/niece went to school today.
백화점에서 조카 선물을 샀어요.
I bought a gift for my nephew/niece at the department store.
주말에 조카와 공원에 갔어요.
I went to the park with my nephew/niece on the weekend.
부산에 가서 조카를 만났어요.
I went to Busan and met my nephew/niece.