This indicator is used to compare the hype of a given market to another.
Green indicates that it is overhyped compared to the base market (BTCUSD by default) and red indicates it is underhyped. If it goes green and then declines, that is a signal that the bull run is likely over. If there is a large dip while RHI is green, that is a signal that the price is likely to bounce back in the next candle.