Below the root, Internet resources are organized into a hierarchy of domains, administered by the respective registrars and domain name holders.
A DNS name server is a server that stores the DNS records, such as address (A, AAAA) records, name server (NS) records, and mail exchanger (MX) records for a domain name (see also List of DNS record types) and responds with answers to queries against its database.
Once you have changed them, it will take roughly 48 hours for the changes to propagate.
To connect your domain name to your website you’ll need to change your nameservers.
A name server is a computer application that implements a network service for providing responses to queries against a directory service.