The phrase "bright smile" refers to a person's cheerful and radiant expression when they show their teeth while smiling. It suggests that the person has a happy and positive attitude.
Strong confident former college football player with strong hands and bright smile just looking for fun times! (meetacrossdresser.com)
She had beautiful brown skin and a big bright smile. (theeverygirl.com)
My husband and I jostle along in our shiny Subaru, weaving around chickens, bicycles and groups of children with bright smiles who wave at the novelty of white faces in their village. (relevantmagazine.com)