To be suave is to be smooth, polite, and a little bit cool. Men can be suave and debonair, especially the ones riding horses on the covers of romance novels.
Suave is from the Latin word suavis which means "agreeable." To be suave is still to be agreeable — a suave person knows how to work the room, and you might want to appear suave and sophisticated when you meet your sweetie's parents. Although it's an old fashioned compliment, suave has morphed into something meaning a little bit cheesy.