When both %bb and are OB/OS then the column will turn blue and a buy/sell arrow will appear in the indicator provided other conditions pertaining to the OB/OS condition in one of the last two candles are also met.
I use this mainly for Cryptocurrencies for shorter time periods to indicate possible trade opportunities.
You could also set an alert on the arrow indicator appearing to auto trade.
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.