You have base values like Hit, and then you have effective percentages like Hit Rate calculated off of them. I'll describe the basic values first.
Hit - your accuracy
increases as you level such that your Hit Rate will be 95% against monsters at your level, and can be increased by Rare/Epic equipment
You'll have higher accuracy against monsters lower in level, and lower accuracy against monsters higher in level.
Critical - critical hits and heals do twice as much
increased by AGI, buffs, certain foods, and some raid armor sets
Unlike in RO1, crits are not guaranteed to hit, as far as I can tell. There's no Lucky Dodge either, for that matter.
Haste - decreases cast time
increased by certain foods, Rare/Epic equipment, and by summoning your Guardian
Despite what the tooltip for the skill says ingame, it does not increase your attack speed.
Vigor - decreases skill cooldown time
increased by Rare/Epic equipment, and by summoning your Guardian
Defense - reduces all damage taken by Defense Rate against an enemy at your level
increased by armor, buffs, and certain foods
Dodge - evades damage entirely by Dodge Rate against an enemy at your level
increased by AGI, buffs, certain foods, and some Rare/Epic equipment
Parry - halves damage taken by Parry Rate against an enemy at your level
increased by STR/INT, buffs, certain foods, and some Rare/Epic equipment