A non-profit is a company that for accounting purposes does not have shareholders and therefore keeps nothing in retained earnings at the end of the period. The leftover money must be distributed (e.g. as salaries, towards the stated mission, etc.). Their financial statements list net profit for the period and nothing is retained.
The money doesn't have to be used. Many non-profits have very large balance sheets of cash and cash equivalent assets. The money just won't be paid out as dividends to shareholders.
