Question

A material through which a current does not move easily is a(n) _____.

Answer 1

A material through which a current does not move easily is called
an insulator.

Technically, charges CAN move through an insulator, but they lose
a lot of energy doing it, so the current that flows through the insulator
is very very small, usually too small to even measure.

Another way to look at it:  Insulators have high resistance.