Here's a basic rundown from http://swtorstrategyguide.org/swtor-stats-attributes/
Power - Generic stat that increases the bonus damage and healing of all of your abilities
Critical Rating – Increases your chance to score a critical hit with all heals and attacks
Surge Rating – Increases critical bonus damage with all heals and attacks. The default bonus is 50% extra damage/heals on a critical hit, which this rating improves.
Alacrity Rating – Decreases activation time for all abilities. Does not affect the global cool-down.
Defense Rating – Increases chance to parry melee attacks and deflect ranged attacks
Shield Chance – For those who equip a shield generator in their offhand slot, increases the chance for an attack to be partially absorbed by your shield
Absorption Rating – Increases the amount of damage reduced when an attack is shielded, requires an off-hand shield generator.