This value is your total Absorption in a military attack.
Each unit "absorbs" a certain amount of base damage in a military attack. This is multiplied by their quality (the percentage assosciated with them).
Total Absorption is the sumation of: (Each troop's base absorption value) * (their quality) * (the amount of each troop).
If this value is higher than your opponents damage OR your absorption times your Damage Value is higher than the product of their absorption value and their Damage Value, than you reppelel an attacker.
This value is also affected by randoms and the spell Valor.