How to grant access to a specific page of the site to a remote employee?

Question

Access rights

Hello.
There is an account on certain sites. The task is to give access to a remote employee, but not to give access to all pages of the site, but only to certain ones, so that he could not access pages that are not related to his tasks, so that there would be permission only to those pages that are directly related to his activities .
Can someone tell me the service or how to organize it at all?