What is resultant force?

In physics and engineering, a resultant force is the single force and associated torque obtained by combining a system of forces and torques acting on a rigid body. The defining feature of a resultant force, or resultant force-torque, is that it has the same effect on the rigid body as the original system of forces.

I hope it's helpful!

it is a force that result in anything to be done

spectral lines lyman is one set