This is a simple Sunder Armor weak aura. It does the following
LOADS: If your class is a warrior and you're in combat
Displays a Sunder Armor icon with text in the middle of your screen.
If there is no sunder armor on your target, displays a large red zero
If there are 1-4 sunder armor stacks on your target, displays the number of stacks with white text. Icon gets progressively more transparent as stacks are applied
If there are 5 stacks of sunder armor on the target, the icon vanishes
If less than 5 seconds remain on the sunder armor debuff, the icon re-appears with half transparency and countdowns the remaining time