Intelligence- Basic intelligence of the character- High intelligence increases the characters chances to succeed in some skills and increases the characters perception. Also a very high intelligence will allow the character to increase the amount of skills he can learn.
Willpower- Willpower is a characters strength of mind- Willpower increases a characters Spirit if he is a psionic user or his chance to defend against mind based attacks.
Charisma- Charisma affects a characters Trust/Intimidate factor
Strength- Affects a Characters ability to do damage. The higher the Strength stat goes the more a character can carry, lift and throw. Physical Strength can also affect certain skills.
Dexterity- High amounts of Dexterity can affect a characters ability to parry, dodge and strike. Also skills that require high amounts of dexterity can be made easier to perform the higher this stat is.
Stamina- Affects the characters Endurance. High stamina increases a characters HP and resistance to Poisons.
Speed- Increases a Characters base speed