The word "electricity" is sometimes used to mean "electrical energy". They are not the same thing: electricity is a transmission medium for electrical energy, like sea water is a transmission medium for wave energy. An item which allows electricity to move through it is called a conductor. Copper wires and other metal items are good conductors, allowing electricity to move through them and transmit electrical energy. Plastic is a bad conductor (also called an insulator) and doesn’t allow much electricity to move through it so it will stop the transmission of electrical energy.