The first three channels are the major American tv networks. ABC, CBS and NBC have local affiliates. The affiliated channels will have a four letter call code, but the symbols seen here will be on the screen at times to let you know which network it is. Watch these local channels at 6am, 6pm and 11pm for the local news to learn about the happenings, weather and sports of your area. (The times noted here are for the EST time zones. Check your local listings for the time of the local news in your US time zone.)
Columbia Broadcasting Network
CBS is national, with affiliates
Consumer News & Business Channel
Public Broadcasting Service
Turner Broadcasting Network
Entertainment and Sports Programming Network
Of course there are many, many more television channels. Check out this link at Wikipedia for more channels.