This feature is only available if enabled through General Settings. If so, projects that the resource has some interest in are listed here. This has no effect on security but notifications can be given to the resources when specified events occur for the project.
You can add projects individually or copy them from another resource. Click Remove, after checking listed projects, to clear the entries.
Any projects you specify here will have this resource listed on their Interested Resources tab. Similarly, if the resource is selected there, the project will be listed here.