Team Roles are the roles each player plays in a team. They are separate from the categories that Heroes are split into in-game.
The DPS roles are usually filled by heroes that deal the most damage. Damage heroes are typically played by the DPS role. They can be split into two kinds, hitscan and projectile. Hitscans characters are heavily reliant on their primary weapons that will have no bullet travel time, while projectiles are characters with either ability reliance or a reliance on a weapon with bullet travel time.
This type of player can also potentially have a flexibility to switch to certain tanks in multi-tank compositions, or Brigitte on multi-support compositions.
The Flex role on a team is usually filled by players that play Offtanks such as Zarya, Dva and Roadhog, as well as players that switch between these heroes and other characters often played by the DPS role and occasionally heroes normally played by the support role. Some secondary supports can also be labeled as flex supports, who will also fulfill the same as before, but instead of offtanks, it will play supports.
The Tank role on a team is filled by the player that is playing the Main Tank in the composition. Typically Main Tank heroes are thought to be Reinhardt, Winston and Orisa. In certain cases, Wrecking Ball is also played as a Main Tank, such as in dive compositions.
The Support role is played by people playing characters that can heal other players (or support them in other ways). Historically, the Support role has been split into Main Support players who play Mercy or Lucio and occasionally Ana, along with a secondary support that can play the rest of the Support cast such as Moira, Zenyatta and Ana. Brigitte is occasionally also played by the secondary support, but is normally filled by the DPS role. The other heroes in other category typically played by the Support role are Sombra, as she provides utility hacking health packs, and Builder heroes (Torbjorn and Symmetra) as they bring utilities with turrets and teleporters, respectively. Certain other common picks for the secondary support role include Roadhog in quick pickoff compositions and Bastion in pirate ship compositions in payload maps.