Your strength determines the physical damage you inflict in close-range combat. The higher the value the more damage you inflict.
You can increase this value further with magic items.

Your intelligence determines the magic damage you inflict in close-range combat. The higher the value the more damage you inflict.
Magic items can increase this value further.

Your agility determines the physical damage you inflict in long-distant combat.
It also influences your success rate when attacking and evading attacks.

Your wisdom determines your success rate for magic attacks and when evading magic attacks.
Can be increased with magic items.

Your constitution determines the level of your vitality and its restoration time.
Magic items can increase this value.

Your spirit determines the level of your mana energy and its recovery time.
Can be increased with magic items.