Choosing the wireless channel to use on your network can be a real pain in the ass; especially if you live or work (if this is a business network) in a densely populated area.
Put simply, channels are the radio ‘frequencies’ which your devices use, to talk to the router to get on to the internet or on the LAN.
If there are too many routers using the same channel in a close proximity, you are more likely to experience a slower connection, connection dropouts, general interference and other problems.