In the bottom left corner you can see the health bar of your currently selected unit. A standard infantry unit usually has 100 fighters, exceptions confirm the rule (gladiators).

Blue points = Full life points

Yellow Dots = Downed but not dead yet

Red dots = The individual soldier is dead

Caution! Your Commander is always in the first unit in the form of a hash.

If your commander dies, you can still use skills, but your morale will be permanently penalized.