This, like other near miss elements, can encourage a player to keep going.
This means you might have the same symbol appearing across the reels, but since they’re not on a wagered payline, or a payline the game offers, you don’t get paid. On some games you have control over the number of paylines you play. The game will tell you the number of lines that are available, and if not directly on the game itself itself, will tell you in the paytable what constitutes a payline for that game.
When you see lines, this is short for paylines, which are preset patterns that, when symbols line up across them in a formation that leads to a pay, you’ll be paid the amount on the pay table. This question came up on a forum I’m a part: When you see a lot machine refer to lines, vs.