It insulates the axon and assembles specialized molecular structure at the nodes of Ranvier. In unmyelinated axons, the action potential travels continuously along the axons.
For example, in unmyelinated C fibers that conduct pain or temperature (0.4–1.2 μm in diameter), conduction velocity along the axon is 0.5–2.0 m/s (as fast as you walk or jog).
I hope this helps have a great day :)