The documents tab on the profile is where employees can store any documents. Documents can be imported by clicking "upload file" in the top right hand corner. Anything added in this tab, can be previewed and exported.
Depending on how the system administrates set it up in hierarchy permissions, direct managers and managers infinite up the hierarchy may have permission to view and or add documents to their employees profiles.
Survey Response Files
There is a survey response files tab in the documents tab on the profile. If an employee responds to a survey and adds a file to a "file upload" question, the file they imported is saved here.