Quaint means strange and unusual in an old-fashioned and charming way. It's a word you'd use to describe a little store that sells tea cozies and antique tea services, or your grandmother's habit of calling the radio the "wireless."
There is a commonly used sarcastic sense of quaint––when something is run down or shabby and you're trying to say something positive, you might substitute "How...quaint" for "How...interesting." In Middle English, this adjective meant clever or cunning. Its origin is Old French queinte, cointe, from Latin cognitus "known," from cognōscere "to learn."