Why does putting wheels on heavy objects make them easier to move?

Hint: Dragging causes friction in the opposite direction. Rolling is used to change the direction of friction such that the friction works in the direction of the motion as well. This makes it easier to roll objects rather than drag or push them.

Complete step by step answer:
Force:
It is defined as a product of mass and acceleration. When an object of mass ‘m’ is accelerating with magnitude ‘a’. then force acting on an object will be F = ma
Friction:
It is the tendency of an object to resist the flow of motion. There are various types of friction. In this case we will discuss rolling friction.
Rolling friction:
Force that resists the rolling motion of an object like a wheel or any other rolling ball.
Rolling motion:
It is a combination of rotational motion and translational motion.
As per question, more force has to be exerted to pull heavy objects when no wheel is applied. There is huge frictional force exerted in between an object and surface. But when wheels are applied to an object that friction is overcome by rolling motion. Contact between an object and surface is reduced on the application of wheels.

Note:
First just look for the main problem in dragging a heavy weight. Next step is to look for the main advantage of using wheels. Afterwards, make an attempt to link these two things and that’s how one can solve such questions in an easy way.