In slot games, a Wild symbol is a special symbol that can substitute for most other symbols to help form winning combinations, much like a joker in some card games. The specific rules and functions of the Wild symbol can vary from game to game.
For example, in some slot games, a Wild might only appear on certain reels. In others, a Wild symbol might also act as a multiplier, doubling or tripling the payout of any combination it helps to complete.
There are also various types of Wilds found in different games, including Stacked Wilds, which cover an entire reel; Expanding Wilds, which can grow to fill up a reel; and Sticky Wilds, which stay in place for multiple spins.
Always check the rules or paytable of the slot game you're playing to understand exactly how the Wild symbols work in that specific game.