What does he mean?

As the story continues, the reader can see that Meursault could even be considered heartless since he doesn't express grief at any given moment and instead goes right back to work, flirts with Marie and even takes her to bed the day after his mother's funeral. Meursault, however, represents Albert Camus philosophy.

Albert Camus believed in absurdity, meaning that he believed life had no true meaning behind it and it was pointless to search for said meaning. Camus makes the reader understand his philosophy through The Stranger's main character, Meursault.