I answered it, "Are you an interpreter, ma'am?" and it marked it correct, but said I had a typo, it suggested "Are you a interpreter, ma'am?". English prefers "an" before a word that starts with a vowel.
Ex: An elephant, an aardvark, an outhouse; a giraffe, a cat, a building
It's a polite form of address for a woman whose name you don't know. Ma'am is a shorter, less formal version of madame. Ma'am is typically used for women who appear to be over a certain age. Young women and girls are often referred to as miss.
Example: In a public space like a store or on the street a woman drops her hat/gloves/bus card/bag or walks away leaving something at the cash register or on a bench, etc. If you see her do this à polite thing to say is, "ma'am is that your ____?"