How can I add a second user to my laptop (see below)?

Someone wants to borrow my laptop for a few days because their computer is broken. I just can't say no and I agreed. But I don't want her to see personal things from my laptop (we're just neighbors and not friends). So can I add something like a second user or something (I have no idea about technology) or any other way so that they can't see my personal data?

Can be answered if the operating system is known.

Yes you can. How this works depends on your operating system.

Here e.g. Instructions on how to do it on Windows 10.
https://www.heise.de/...58638.html

I have windows