BBI (Bull and Bear Index) is an indicator aims on measuring the general short/mid-term (< 1 month) trend and sentiment of the stock/market. It used an average of 4 SMAs (3, 6, 12, 24) as a cut-off of a bullish/bearish trend. In general, YMMV, you can enter when close> BBI and exit when close<BBI.
BBI Bollinger Bands uses BBI as "basis" and calculates variations (Stdev) of BBI during the past several days. In general, BBI Boll band is more volatile than the traditional Boll Band.
The "possible entry and exit" function is for fun, trying to spot the point where there is extreme fear and optimism, not necessarily working yet.