Each character has a set of stats: Health, Magic Points, Strength, Magic, Agility, Vitality, and Will.
Health increases the number of hit points your character has, and is lowered by enemy attack hitting that character. If your hit points reaches 0, that character becomes unconscious and can't fight until they are revived or the battle is over.
Magic points increases how many techniques you can use, and is reduced by using technical attacks like insane strike or magic attacks like heal. When your magic points reaches 0, you cannot cast special attack like heal until the battle is over, whereas you restore a small amount of magic.
Strength increases the damage you deal with physical attacks.
Magic increases the damage you deal with magical (Ex, fire, ice, thunder) attack, and the damage you restore with heal.
Agility determines whether you or the enemy goes first in a battle.