2001:2b8:bc::/48 - KRNIC-NET
inet6num: 2001:2b8::/32 netname: KRNIC-NET descr: Korea Internet Security Agency country: KR admin-c: IM574-AP tech-c: IM574-AP status: ALLOCATED PORTABLE mnt-by: MNT-KRNIC-AP mnt-irt: IRT-KRNIC-KR last-modified: 2017-01-03T07:46:34Z source: APNIC
IP address ranges, or netblocks, are groups of related IP addresses. They are usually represented as a base IP address, followed by a slash, and then a netmask which represents how many IP addresses are contained within the netblock. This format is known as CIDR. You'll also sometimes see netblocks given as a start ip address, and an end ip address, or an ip address range.
Traffic works its way around the internet based on the routing table, which contains a list of networks and their associated netblocks.