You can still receive a salary, and as far as I know there are no limits on what you can pay yourself. However, you must have a predefined salary and you are audited regularly to ensure there isn't fraud. However, outside of the overhead (salaries, office, servers, etc) any further profits have to be reinvested into the business. This means that if they get 5 million dollars and only spend 4 million, no one gets to take home the extra million. It has to go back into the business.
This is in contrast to for-profit companies where that money can go to the owner (private company), or to shareholders (public company).
The Wikipedia link posted above probably has a better explanation, this is just my understanding due to my SO working at one.