The information that staff are able to see when viewing a colleague's profile is very restricted.
They will see the user's wall:
A very basic version of the user's Public tab:
And have access to the user's Files tab.
Staff will not have access to the documents stored here unless it has been shared with them specifically. You can read more about file permissions here.
Additionally, you may wish to allow staff to view their colleagues' working patterns. In which case, the Working Patterns tab will be available when viewing their profile. Staff will only see the user's existing working pattern. Read about how to manage permissions here.