The Save Results Window presents a report of the items being saved to SharePoint/Office 365. It will present items successfully saved and also any items where the item was not successful. For example, in the event an item of the same name already exists in the library (and overwrite existing files has not been selected).
The Save Results windows can be suppressed in the Settings window for all save operations.
In addition, you can overwrite the suppress results window in general settings for specific favorite locations.