The Vietnamese word "bộ đội" refers to a soldier or a member of the military, particularly in the context of the communist military forces in Vietnam. It is often used to describe the soldiers of the People's Army of Vietnam.
Bộ đội Việt Nam luôn sẵn sàng bảo vệ Tổ quốc.
(Vietnamese soldiers are always ready to defend the homeland.)
Tôi thấy bộ đội đang tập luyện trên sân.
(I saw the soldiers training in the yard.)
In summary, "bộ đội" is an important term in Vietnamese to denote soldiers, especially in relation to the communist military.