The potentiometer is a resistor with a variable tap. It has three ports. The resistance refers to the value of the fixed greetings. The pick-up can be moved mechanically and provides a value between the minimum and maximum resistance value on the third terminal. The potentiometer also has a maximum power - for us about 1/8 watt - which can easily be exceeded if you connect the tap directly to the voltage source and one of the other two connections.