In an incandescent lamp bulb you find a thin wire having a resistance of only a few ohms. In the circuit, the wire heats up so much by the current flowing through that it starts to glow.
How much current flows through a resistor at a fixed voltage is described by Ohm's law. How much heat is generated at a resistor is described by Joule's law.
In the next steps are you looking at what changes in a circuit if you use multiple resistors.