This is a new version of the commonly know Bollinger Bands indicator. It measures the distance between the Upper and Lower bands - the bandwidth. When below 4 the market is over-compressed getting ready to break out and when it is above 11 the market is in a significant move where trading opportunities may be large.
Between these numbers the currency pair is weak or compressed and has limited movement which may be hard to trade profitably.
Similar to the Bollinger Bands indicator you are able to adjust the Period and how many Standard Deviations you want the bands to be calculated on.