Hostname or VPS Name is an identification which is a name you give to identify a server. So it means you can choose any random name as it does not affect the functionality of the VPS itself.
For example, you can choose server01 or a domain name like server.example.com.
Note: Please DO NOT use [space], special characters like (:@#$%^&()/\), http:// or https://, email address. It will break your order.
You can also leave it blank while making the purchase, and the platform will randomly assign a standard name to the VPS. You can always change it later from your administration panel.