Characters in FlexD6 have 4 main attributes. Within those attributes are skills, which indicate what the character is good at. Above all, the character has a Role which classifies the character for narrative and is used to determine the character's specialized skills and ability.
There is no class system in this game. It is all driven by the skills and special abilities you pick for your character, allowing you to create very unique characters.
The role classifies the character for narrative and is used to determine the character's specialized skills and ability. When assigning skills, consider the role and what types of skills that role would have. For example, in a fantasy setting, some common roles would be Cleric, Magic User, Fighter, or Rogue. In a space setting some roles would be Pilot, Smuggler, Bounty Hunter, or Engineer. Each of these roles will have skills and special abilities which align with the role. In all honesty, you can pick any combination of skills and abilities you like. There is nothing in the game that limits you.
See Attributes, Skills, and Special Ability.