This indicator gives you the percentage movement of each candle. Measurements are taken between the candle High point and Low point, and also between the Open and Close and calculated in percent %. From there it smooths out the data with a moving average. This gives you an idea of how much volatility is within each candle given the time resolution of the chart.
I like to use this information as a way to turn off a strategy, or select a proper time resolution for a strategy. If each candle has less than 2.5% Volatility most strategies will typically buy and sell rapidly at prices that are too close together, potentially losing money. During those times it seems best to either temporarily turn off the strategy, change the time resolution or switch to another strategy.