In a Team Edition setting, there are 4 possible options for the visibility of a given client item (this setting specifically pertains to any given Whiteboard, Session Notes, Journal Entry, Metric or File), like so:
Here is exactly what each one means:
Generally visible - This means that anyone who can see that client's Client Page WILL be able to sett that item. This includes the client herself, her coach, and any other coaches (or admins) who have at least "read only" access to that client. This also includes Company Personnel, provided they are specifically granted access to view items of that type for clients from the same Company.
Visible only to team coaches - Like it says, only team coaches: not the client, nor any company personnel. Which coaches? Only those coaches (or admins) who have "read only" access or better to that client.
Just me and the client - This means only the client and the to coach who shared or created the item will be able to see it. Admins, other coaches, and even the client's Primary Coach (when someone else) will not see it.
Private, for my eyes only - This means only one specific coach will ever see it, namely the one who created or shared the item. Admins, other coaches, and even the client's Primary Coach (when someone else) will not see it.