What are nameservers?
Nameservers are DNS servers that link domain names to IP addresses, essential for the operation of online services.
Name servers are equipment that runs DNS servers. Their role is to connect the name of a domain to the IP address of the equipment that provides services to that domain (mail, web, ftp, etc). Without setting correct name servers on the domain, it will not be able to point to the equipment where the files are hosted, emails, etc.