This will plot your choice of OHLC (or any of the averaging choices) of the current candle compared to the previous candle.
For example if you choose "high" for the input and set the chart to daily, you'll see the currently daily high vs the previous daily high.
Green candle represent a higher high and the length of the candle represents how much higher.
Similar to the RSI Cave idea, this plots daily Average True Range values on lower timeframes, as well as the daily open level, which is show as a grey dotted line. Basically a simple way to visualise basic mean reversion stuff