Ron is a guy who Mary Cooper was in a relationship with and was having sex with him which Sheldon could see through the window of his childhood home, which scared him. She met him at their Bible study.
Later, Sheldon tells his mother that he saw everything and he sexually condemns her (due to her religious beliefs) and for this, she sends him to his room.
Howard talks to Sheldon and the former tells the latter not to stand in the way of his mother's happiness. Howard also tells Sheldon that he had a simple experience like this with his mother after his father left.
He isn't seen on-screen.