This indicator uses different volatility channels - Bollinger Band, Donchian Channel and Keltner Channel width to measure volatility.
Indicator plots channel bandwidth percentage with respect to close price.
This is not same as Bollinger Percent B - which is measure of where price is with respect to band. Instead this indicator is similar to ATR Percent indicator published here: tradingview.com/script/TIdaziId-ATR-Percentage/
Plotting is color coded to indicate volatility zone:
Red : Extreme volatility
Orange : High volatility
Lime : Low volatility
Green : Extreme low volatility
These levels are again derived by long period bollinger bands