What is the best and FREE video editing software for PC windows 10?

Best and free doesn’t always go hand in hand. Use pirated software if you don’t have a budget to buy them right now.

Anyway, Windows 10 has a built-in free screen recorder.
https://betanews.com/2019/01/14/windows-10-scre...

Alternatively you can also use OBS. Very good software for recording screen.
https://obsprojec...m/

For editing..

OpenShot (https://www.opensho...g/)
Shotcut (https://shotc...rg)
HitFilm Express (https://fxhome.com/e...ss)

cracked Premiere Pro , if you count it as free.
If your YouTube channel gets big and popular and you have money to spend , consider paying for it.

Handbrake is an excellent free video editor. Could try that. The UI might confuse some though.

OBS is probably the best screen recording app which is free. But if you have a decent enough GPU then you should have Shadow Play built in, which has far superior quality than anything I have ever used.

Try OpenShot Video Editor it is free, open-source video editor for Linux, Mac, and Windows. Easily cut, slice, and edit any video or film.
https://www.opensho...g/

Camcapture is a free screen recording software.

Try this, lightweight and has a lot of features.
https://www.nchsoftware.com/videopad/inde...ml

Free version’s direct link.
https://www.nchsoftware.com/videopad/kb/fre...ml