When you level up the color meanings are
Red=Strike up
Blue=Power up
Yellow=Event up
Light blue=Hide up
Violet= Use up
Orange=Reverse up
Purple= Z up
Black= Health
White= Random it's mostly gives you a new skill card or a new event card.
Another thing is if you see a capsule with a yellow square on it that means you will get more health from that capsule rather then a capsule without yellow in it.