It's a bonus paid after spending n months in a warzone.
e.g. After 4 calendar months, $5000, after 8, $10,000.
Hazard pay is usually some percentage on top of base pay and if you're "lucky" and qualify for "living condition pay" it's another percentage on top of that. I have some associates here in the D.C. area that tell me at the height of the Iraq War they were pulling down ~$300k/yr all added up, on base salaries of $80-90k.
