In short, power factor is the ratio of the real power consumed by a gizmo to the apparent power needed to be generated and delivered by the power company.
The reason for this “extra power” from the power company is the inductance and capacitance in your gizmo that results in shifting the AC current sine wave away from being perfectly in sync with the voltage sine wave.
You don’t really need to understand how all that works; just watch the vid to see why it matters!
And that’s all there is to it.
One last tip I neglected to mention in the video: You may notice when purchasing a UPS (battery backup) for your puter that they are rated in VA (volt-amps) instead of Watts.
VA is basically apparent power, and W is real power.
So, a 500VA battery backup will not supply 500W, but less than 500W due to power factor. How much less real power the UPS can supply depends on the PF of the load (computer and monitor) attached to the UPS.
Isn’t this fun? 😉