Is the notebook fully usable after switching off Windows S?

Is a newly purchased notebook still just as usable in its functions if you switch off Windows S (I know that can't be undone), e.g. To load apps from the Google PlayStore? Or does it affect something?

Yes, you can do a lot more then! With Windows 10 S you can only install programs from the MS Store with standard Windows 10 you can do everything.

And if Windows is deactivated, does the notebook (medion akoya e3221) run under windows 10? Unfortunately, I can't find any information about this

Oops… Isn't it in the description? WINDOWS 10 HOME. Who can read has a clear advantage ;-)

Right!