Conductor: conductors are those substances that conduct electricity and heat. Eg. Metals like iron
Insulator: Substance that do not allow heat and electricity to pass through. Eg. Wood, Rubber etc.
A conductor is something that allows the current or electricity to pass through it.
We have Metals, wires, water (Tap water), Human body etc, these things are considered as the conductors because they can easily allow the flow of current through it.
An Insulator is something that doesn't allow the current or electricity to pass through it.
We have plastics, clothes, rubber, glass, PVC, wood, bricks, paper stones, etc, these things are considered as the insulators because they do not allow the current to pass through it.