From: Tucson, AZ
The counter colored indicators give an general summary of status, like readiness and supply. From green to red, many shades. As you move a unit, it uses up supply, so it will impact the color. If use it in combat, it uses up supply, readiness, and suffer attrition. Resting units in good supply with no combat will tend to green as they recover.
Basically, a quick easy to recognize indicator for what units you want to use in combat, and those you don't. Red will still fight, but your suffer for it. Sometimes you don't have a choice, but its to help you to know what units need to be rested and what units a ready to go!
He's refering to the dots on the LEFT side of the counter. But thanks for the info. You go guy.