This policy setting allows you to change all instances of the label SharePoint that are displayed on the Save to SharePoint ...

This policy setting allows you to change all instances of the label SharePoint that are displayed on the Save to SharePoint form in the Backstage view for Word, PowerPoint, Excel, Visio, and Project.

If you enable this policy setting, the new string you provide will be displayed for Save to SharePoint in the Backstage.

If you disable or do not configure this policy setting then the default string, "SharePoint," will be displayed for Save to SharePoint in the Backstage view.