what is the purpose of a resistor in an electrical circuit

A resistor is a part of an electrical circuit that helps to regulate how much electricity flows through the circuit. It's a bit like a water tap in a pipe. The tap can be opened or closed to control how much water flows. In the same way, a resistor can be adjusted to control how much electricity flows. With too much electricity, the circuit might overheat or get damaged, so the resistor helps to keep it running safely.