The Vietnamese word "đại biện" refers to a diplomatic title that translates to "charge d'affaires" in English. This term is used to describe a diplomat who is temporarily in charge of the affairs of a diplomatic mission, usually in the absence of the ambassador or the head of the mission.
While "đại biện" primarily pertains to diplomacy, it could also be used in a broader sense to describe someone who is acting on behalf of another person or organization in various contexts, though this is less typical.