Volatility indicators can tell you how large the up- and down-swings are for the current market environment. When you see strong price fluctuation, there is high volatility and when not, there is low volatility. Making this distinction is important when considering a trading setup, as it will impact position size and stop / target levels.
When used with time based bars, the Volatility Stop indicator adjusts to the current market environment. Specifically, it allows for stop widening when volatility increases and tightening when it decreases.