Nabble hosts tens of thousands of forums. It spreads the load across a number of servers. n8 is the Nabble server on which your forum is hosted.
Each forum on each server needs to have a unique name. Many forum owners embed their forum within their main site and, understandably, give them names which are the same as others that have already been created. Adding a further random set of numbers ensures that each forum on each server has a unique address.
If you do not plan to embed your forum within another site (where the URL of your forum becomes largely irrelevant to ordinary users) then you need to register a domain of your choice and use the settings at:
Options > Application > Change domain name
to make sure that requests to your domain name get redirected to the appropriate forum on Nabble's servers.
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.