In casino slang, hot describes anything that seems to be winning: a player on a strong streak, a craps table where shooters keep making their point, a blackjack table where players keep beating the dealer, or a slot that has paid out several times in a short spell. Calling a machine hot is usually meant as a friendly tip about where to play.
The opposite is cold. Mathematically, neither label predicts anything. Each spin of a certified RNG slot and each roll of the dice is independent of the last, which is why trusting streaks is tied to the gambler’s fallacy. Operators still use the language in marketing, such as “hot games” rails in the lobby ranked by recent wins or play volume. That is fine, as long as it never suggests better odds.