This command sets the name of the server that the services' clients run on. This will show up when people /whois any of the nicks services use or in a /link command. The default setting is services.net.
Example:
/as services set servername services.net
The server name is another aesthetic detail that allows you to customize your network. You can make it look more professional or more personal as you see fit. For other commands that customize the appearance of services see SET USER and SET HOST.