service organization; volunteer group
Refers to a group that performs unpaid community service, such as a Rotary Club, Lions Club, or local volunteer association.
He does volunteer work at a local service organization.
ボランティア団体 is a broader term for any volunteer group, while 奉仕団体 often implies a more formal service club with a structured mission.
Compound of 奉仕 (service) and 団体 (organization).