Force describes the effect one body has on another. Force is transferred from one item, such as a hand, to another item, such as a ball, with a magnitude, direction and point of origin. For example, if you push a ball at one point with a certain amount of force in one direction, then it will move differently than if you push a ball at a different point with a different amount of force and direction.
Rotational inertia is the tendency of an object to resist a change in its rotation. An object with a high rotational inertia will take more force to make it rotate and more force to make it stop, than an object with a low rotational inertia.
An object is in equilibrium if all the forces pushing on it in three dimensions are equalized such that it does not accelerate in any direction. An object that is already moving and has an unchanging velocity is also in equilibrium, because it has no force accelerating it in any direction.
Similar to linear equilibrium, rotational equilibrium describes a situation where all rotational forces on an object are equated so that it does not rotate in any direction. The rotational tendency due to application of force to a point is called the "moment." Rotational equilibrium happens when all moments are equalized.