Futsal tables work like soccer tables: 3 points for a win, 1 for a draw, 0 for a loss, ranked on points, with goals for, goals against and goal difference beside them.
What changes is the scoring rate. Futsal is played five-a-side on a hard court with a smaller, heavier ball, and games regularly finish 6–4 or 8–5. More goals means goal difference moves fast, and one lopsided result against a weak team can carry a lot of weight. Plenty of indoor leagues cap the goal difference a single game can add for exactly that reason.
Under the Futsal Laws of the Game, a match is two 20-minute halves on a stopped clock. Rec leagues usually play a running clock to fit court bookings, which is worth knowing when you compare scores across leagues — it is not the same game length.