I am using three L298N Motor Drivers (similar to the one in the image attached) for a 6WD rover. I am using PWM to control motor speeds for the first time and noted that the cap like thing on the enable pins can be removed after seeing this video. And when I remove them I see a total of four pins. What is the purpose of four pins when we are using only two (as used in the video)?
The "caps" (jumpers) connect the enable pins to a pullup resistor that keeps them constantly HIGH if you don't want to use them. If you do, remove the jumpers and connect the wire from Arduino output pin to the now empty pin closest to the edge of the board. The "cap like" things are Berg jumpers.