Re: how to upload/add multiple keyword labels at a time in AdWords?
Go to Specific Campaign or Adgroup. Click keywords tab.
Click Columns > Customize Columns.
Add the Attribute 'Labels' and Apply it.
Click Edit > Download Spreedsheet. ( Download Excel format .xlsx).
Now, edit labels in offline and save.
Go to Edit > Upload spreadsheet. Upload your edited spreadsheet.
That's it you are done.