An attaché is someone who works in an embassy — a country's office in another country — and looks after one special subject. A military attaché deals with armies and defence; a cultural attaché deals with art, language, and visits; a press attaché talks to newspapers. They are not the ambassador, the person in charge; they are “attached” to that office to do one job. The word still feels French and a little official. You meet it in the news, not in the school corridor. It is said a-ta-SHAY, not like attach. Though actually, English also pinched the same spelling for a thin hard briefcase (an attaché case), but that is a bag, not a person, and younger people usually just say briefcase. Some writers drop the accent and write attache; the sound stays the same.