This indicator uses rate of change (ROC) indicator and its standard deviations.
ROC values are cycling around zero, i.e. around the mean.
Two standard deviations of the ROC draw the upper and the lower bounds that serve as thresholds.
These capture outliers that can be used as signals.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.