Comeliness is the quality of being pleasant to look at in a quiet, seemly way — the attractiveness of a comely person. It is an old, bookish noun. You are more likely to meet it in a story set in the past, or in a careful, slightly formal sentence, than in a café. It does not mean “sexy” or “glamorous.” It is closer to a wholesome, fitting prettiness, the kind older writers praised in a face or a figure. Though actually, even those older writers used it most about women; using it about a man is possible but rare and will sound even more old-fashioned. Students do not need this word to talk about beauty today — pretty, good-looking, beautiful will do — but they may need it to read.