A few examples of what some capital letters stand for;

SL -stop loss
T/S or T/SL - trail stop loss - moving it up/down with the price change to secure profit
TP - target profit or target pips
RR - risk/reward ratio
S/R level - support/resistance levels
BB - Bollinger Bands (BBM middle, BBU upper, BBB bottom)
MA's - moving averages (EMA exponential moving averages, SMA simple moving averages)


Buyer (Bulls) - going long, buying.
Sellers (Bears) going short, selling.