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. Red candles represent a lower high than the previous day and the length is by how much lower.
This indicator is pretty straight forward, look for me to build on this with something a little more elaborate in the near future.