Hypoplectrus puella has a deep body and head which is highly laterally compressed with a straight forehead and a rather short snout and a protrusible upper jaw. It has an angular preoperculum which has serrations on its edge and a number of small forward pointing spines on its lower margin close to the angle. The continuous dorsal fin has ten spines and 14–17 soft rays. It has long pelvic fins which extend as far as or beyond the anus. The caudal fin is slightly forked. This species has a pale yellowish to tan head and body which is marked with as many as 7 dark brown vertical bars which are variable in their number, darkness and length. They are predominant coloured browns and yellow, although some fishes show blue hues. Their large and noticeable pelvic fins vary in colour from yellow to dark bluish brown. They may also have thin, iridescent blue lines on the head and, rarely, these are also on the body. This species attains a maximum published total length of 14 centimetres (5.6 in). Hypoplectrus puella is found in the central western Atlantic Ocean and is the most numerous and widespread species in the genus Hypoplectrus. Its range extends from Bermuda south to the Florida Keys and the Bahamas, into the Gulf of Mexico and from Tuxpan in Mexico along the northern coast of the Yucatan Peninsula to northwestern Cuba, and the whole of the Caribbean Sea.
