Nameservers play an important role in resolving names in the Domain Name System (DNS). They manage the information on which IP addresses correspond to which domains. For example, when a domain is called up in an internet browser, the required IP address for that domain is requested from the registered nameservers. If there is a DNS zone for the domain on the corresponding nameservers, they provide the IP address to the internet browser, which then attempts to retrieve the webpage from the webserver assigned to the respective IP address.
For domains registered with Emubox, the nameservers of Emubox are registered by default.
Detailed information on the topic of nameservers can be found on Wikipedia.