For each bar on the chart, the script calculates at that point for multiple lengths (e.g. 3, 7, 14, 16 etc) and displays them vertically top to bottom, fastest to slowest respectively. It indicates the actual reading (0 to 100) by way of a colour (green for overbought, red for oversold).
So for example, if the indicator shows a cluster of reds, you know that price is oversold on several lengths simultaneously.
Idea was taken from an article.