[Potironette]

Thanks for answering!

So..
Energy is the ability to do work, and this is measured in Joules (Nm)
Kinetic energy is one form of energy (the other being potential energy). And this always positive, as KE = 1/2 * mv^2, and the only variable that can be negative is v, but v is squared so Kinetic energy is always positive.

What does "transfer of energy" mean..?

In measuring the "transfer of energy," work is what measures the difference between the final state of kinetic energy from the initial state of kinetic energy as KE_f - KE_i. If KE_f is greater (by having greater speed, v), then work is positive because energy was gained through the "transfer." If KE_f is the same as KE_i (by having same speed, v), then no work has been done because no energy was lost or gained. If KE_f is less than KE_i (by having slower speed, v), then negative work was done because energy was lost in the "transfer."

Is "transfer of energy" just related to the speed of an object and thus it is measured by comparing the final state of kinetic energy to the initial state of kinetic energy?

Work itself measures kinetic energy focusing on how one force acts with a distance, or on how one force changes an object from one speed to the next (or does this have nothing to do with speed?) while net work measures how multiple forces are acting with distances...and that can be measured too from the difference between KE_f and KE_i?