How does pay work in the army?

The service is responsible for housing/paying and feeding you. If you are unmarried, then you will (normally) live in the barracks and eat at the DFAC as part of your contract.

First, if money is the only thing that is getting you to put on a uniform you may want to rethink the decision. Second, you get base pay, that's it. Housing and Sustenance Allowance are authorized for married personnel and those of certain rank, position, or duty assignment.

If money is a driving force in your life, then you will be disappointed in the Army. As the old adage goes, "They say that in the Army the pay is mighty fine, they give you 100 dollars and take back 99."