A bear is a person who watches the price of this commodity fall. Bulls are the opposite. It means you see that this thing is going to fall. You sell it now. His price has fallen, so you can buy it back and close your position. Bulls are the opposite. Look, this thing is rising. If you buy it now, you will make money if the price goes up.

The meaning of length is similar to what I said above. Going long is bullish, buying up and shorting is bearish. Hold on for a long time