If an object is moving, inertia is resistance offered by the subject matter on its motion
The moment of Inertia (MI) is the product of the mass of the object and square of the distance of it from the axis.
Or, I = MR2
Or in other words, the physical significance of the moment of inertia is the resistance offered by the body to its rotational motion. This resistance tends to slow down the speed of the object and ultimately it will stop until an external force is applied to it.