The Vietnamese word "đại sứ" means "ambassador" in English. An ambassador is a person who represents their country in another country, usually in a formal diplomatic role. They work to maintain good relationships between their home country and the country they are assigned to, often dealing with political, economic, and cultural issues.
In general, "đại sứ" specifically refers to the concept of an ambassador in a diplomatic sense. However, in a broader context, it can also symbolize someone who represents or advocates for a particular mission or cause in various fields, such as culture or business.