Who is Masson?

Masson is the friend of a friend to the main character. Meursault's friend Raymond introduces him to Masson, who owns a bungalow by the sea. Masson is married. Meursault and Marie vacation with Masson and his wife. Masson is described as gregarious and generous to his guests and testifies on Mersault's behalf during the trial later in the book.
However, we are meant to perceive Masson as a somewhat simpleminded individual. He is hospitable to his guests, but he is not remarkable in any particular way. The narrator observes in chapter 6 that "[Masson] was rather slow of speech and had, I noticed, a habit of saying 'and what’s more' between his phrases—even when the second added nothing really to the first."
Overall, Masson is a minor character within The Stranger and serves as a carefree, one-dimensional foil to Mersault's complex disillusionment and unhappiness. Meursault views Masson and his wife and briefly conceives of being married to Marie, of having his own, bland, normal, content life with all its traditional conventions. This, however, is a fleeting feeling, just as Masson is a man who makes only a fleeting impression.