This mode is used in order to see /chatops messages occurring on the server and network. Since globops should be reserved for very important oper-only messages, chatops alow opers to communicate about less important things. If an oper is very busy they might turn chatops off, but they should still remain +g. Exactly how chatops are used will depend on the network, but they can be used simply as a way for opers to chat and have fun or for less important but still network-related oper-communications.
/mode Dan +b