The army uses a pay grade system to determine salaries, which can be a bit confusing at first. But think of it like a video game: as you complete missions and gain experience, you level up and unlock new rewards (or in this case, a higher salary). The pay grades are based on your time in service and your rank, so as you move up the ranks, your salary will increase accordingly.
For instance, if you're a private (the lowest rank), you'll start at the bottom of the pay scale. But as you gain experience and get promoted to corporal or sergeant, your salary will increase. It's like getting a raise at your job, but instead of asking your boss for a promotion, you'll be earning it through hard work and dedication.
