Bullish/Bearish Trends..Best way to understand it is to read up on it, link below, on the chart below it is shown as a Blue Dot currently above the Candles, when it drops below the candles it means the Bulls are taking over...
Notice on May 18th the short on MJLB stopped the Breakout and stopped the P-SAR from Dropping to the Bulls...
P-SAR=Parabolic STOP AND REVERSE..Meaning Reversal of-a Downtrend when it drops below the Candles. Technical players usually will start Buying after the P-SAR Drops to the Bulls...