The script is inspired by Bollinger bands but instead of applying them on the price, they are applied on a RSI oscillator. The standard deviation is not plotted against the average like in normal BBs but instead is based on median values (equivalent of a Kijun in Ichimoku ). The goal is to better identify excess in prices that offer good entering points. The usage of a median provides a clearer view of ranging market (ie. the line will be flat).
I use it for long-term investments on stocks to find "fair" entry points. After picking a list of stocks of interest based on fundamentals, I switch to a weekly view. If the stock RSI is under the bands, it indicates that we are in favorable conditions for a buy. For an accurate timing, you can switch to the daily chart and watch out for either a break or a reintegration in the bands. This is your signal.