A pulley is an example of a simple machine that is made up of ropes and wheels.
Mechanical advantage refers to the number of times that a simple machine multiplies the input force.
This means if a simple machine has a mechanical advantage of 5 then it means that it made the work done 5 times easier than without it.
It also means that one would apply 1/5 times the force they would have applied without the machine.
In this case, the pulley which is a simple machine requires you pull 3 times the amount of the rope. Therefore, the mechanical advantage of the machine is 1, which means the output force is equal to the input force.
