Tags are required for the Item Description for any geographic information system (GIS) service that is being shared with ArcGIS Online. Currently, your service does not have any tags. If you plan on sharing this service with ArcGIS Online at a later date, add tags to the Item Description.
Enter tags on the Item Description tab on the Service Editor dialog box before publishing the service.
When serving content, it's important to provide tags for your service so that consumers can search and easily find the service. Tags can be added by accessing the Item Description tab on the Service Editor dialog box and populating the appropriate field.
The Service Editor dialog box can be accessed from the main menu in ArcMap by clicking File > Share as > Service.