The 8 equals what I add to the d20 roll when I roll for the Talent. 

Talents and Stats do have their own seperate rolls, but plain Stat Scores are rarely rolled, most of the times they just add to your Talents. If it wasn't for them adding to your Talents, then you wouldn't succeed on anything most of the time XD. The Stat that goes with a Talent represents the natural ability of your character that would enhance said talent. 

For instance, the Knowledge Talent is generally enhanced by intelligence, or Aptitude in this case, as knowledge is in real life. If one is more Charismatic, then they will be better at Negotiating. If one is more dexterous and quick, then they will be better at Acrobatics. 

So sometimes Stats will be rolled plainly, but not always. Most of the time, its Talents.