Volatility in slot machines refers to the risk and reward profile of a game and how it pays out over time. Low volatility games offer more frequent but smaller wins, providing steady gameplay. High volatility games offer less frequent but larger wins, which can be more exciting but also riskier. It's important to choose a game with a volatility level that matches your bankroll and playing style. Watching gameplay videos on YouTube can help you understand a game's volatility before playing.