DNS means domain Name system. It came along after WINS because not every network needs static IPs. DNS translates host names into IP addresses, then sends the IP addresses to DHCP, which in turn assigns them to the clients on the network.
So, basically it turns the PCs name into an IP address and gives it to DHCP, a separate protocol that gives them out.
This just means that the network administrator doesnt have to assign a static IP to every device that joins his/her network.