Broadcast address refers to the ability to address a message that is broadcast to all stations or hosts on a network. The IP address 255.255.255.255 (in binary, all 1s) is the general broadcast address. You can't use this address to broadcast a message to every user on the Internet because routers block it, so all you end up doing is broadcasting it to all hosts on your own network. The broadcast address for a specific network includes all 1s in the host portion of the IP address. For example, on the class C network 192.168.1.0, the last byte indicates the host address (a 0 in this position doesn't refer to any host, but provides a way to refer to the entire network). The value 255 in this position fills it with all 1s, which indicates the network broadcast address, so packets sent to 192.168.1.255 are sent to all hosts on the network.
Network is required for kernels greater then 2.0x. This line is redundant and can be left.