When to use volunteer work in Korean
Korean: 봉사[ bong-sa ]

When to use it
봉사 means volunteer work, or helping other people without getting paid. You use it when talking about kind activities like cleaning a park, helping at a shelter, or serving food. People often do 봉사 at school, in their neighborhood, or on weekends.
Example sentences
저는 토요일에 공원에서 봉사해요.
I do volunteer work at the park on Saturdays.
우리 학교는 매달 봉사를 해요.
Our school does volunteer work every month.
엄마는 주말마다 도서관에서 봉사해요.
My mom does volunteer work at the library every weekend.
친구와 같이 동물 보호소에서 봉사했어요.
I did volunteer work at an animal shelter with a friend.
여행 중에 해변 청소 봉사에 참여했어요.
I joined beach cleanup volunteer work during my trip.
마트 앞에서 봉사하는 사람들을 만났어요.
I met people doing volunteer work in front of the mart.