They are the levels depicting how close you are to a ban..
1 warn and you're in the yellow.. 3/4
2 warns and you're in the orange.. 2/4 or 1/2
3 warns and your in the red.. 1/4
4 warns and your BANNED.. 0/4
Double warns are possible based on whatever your getting warned for..
And, you Drakue, can test out the warn system by going to your profile, clicking on the edit button next to "Warning Level", and then you'll see how it works..
Wow that is quite a flawed sentence....