Health
Health (also hit points (HP)) refers to the amount of damage on creature can endure before it dies.
Health, or HP, refers to how much damage it takes for one creature in a stack to die. i.e. If I have 23 Troglodytes, which have 5 HP each, and my enemy deals 17 damage, I lose 3 Troglodytes and my 20th Troglodyte has only 3 HP left.
Health also determines the amount of experience you get after each battle.