Volatility is a statistical measure of how much a price moves around its average. In forex, it is usually reported as the average daily range in pips or as annualized percentage volatility. GBP/JPY and gold are consistently high-volatility instruments; EUR/CHF was historically low volatility until the 2015 SNB floor removal made it briefly the most volatile FX pair on earth.
Higher volatility is not good or bad — it just requires wider stops, smaller position sizes, and more disciplined entry criteria. Most systematic strategies explicitly scale position size by recent volatility so that expected risk per trade stays constant across different market conditions.