Online slots, more over all casino games, have a targeted payback percentage built into their ICT-program. In other words: slot games are programmed to pay out slightly less than their real payback percentages in order to make a part of the expected returns. That part of real cash goes to the casino itself in order to be profitable. There is nothing wrong with that. Besides this, keep in mind that all results of your gameplay are completely random because of the random number generators (RNG).
Most players assume that a slot game has to have traditional paylines. Paylines are invisible lines in which symbols must form a certain patron to realize a win. You have two options: slots with and slots without paylines. These paylines can be single or multiple. They act in a straight line, diagonal or zig zag. Anyway: when you get one of these alignments you win! The difference with 'no paylines'-slots is that these slots just need specific symbols to appear anywhere on the reels to trigger a win! Another (nick)name for this is '243 ways to win'-games due to the large amount of possible combinations that enable payouts. The more paylines, the more chances of winning. On the other hand: higher winning chances often means lower payouts!