It is an update for various office components but it breaks the Outlook folder pane in these office 2013 versions:

 

• Office 2013 Standard
• Office 2013 Professional Plus

You can uninstall it, but that has not fixed the issue for me. 
http://blogs.technet.com/b/office_sustained_engineering/archive/2013/09/11/outlook-folder-pane-disappears-after-installing-september-2013-public-update.aspx