netbios is the serviice used by Windows for File and Printer sharing. Normally it's a good idea to disable this on a standalone machine, or block ports 137-139 from internet access. As to where you disable this, it's usually in the Windows network setup dialogs.
NetBIOS is an implementation of an older protocol, NetBEUI, but over IP. These days it's sometimes a check box on the TCP/IP settings for a network adapter. But as it's been pointed out, it is considered insecure and you don't want it enabled on anything that is accessible from the internet. On a Intranet/LAN environment, it might be considered.