TMC and TP are only available in Europe. TP is Traffic Programme, a radio station which sends traffic information every once in a while. If TP is turned on, MP3 or CD would mute and you would hear the traffic information.
TMC is the Traffic Message Channel, another European thing. TMC is transmitted in the background as digital information and used by the RNS-E to calculate a new route if there is a problem on your current route. Youc an also receive TMC information before you get into your car and after you left it and listen to them in your native language (e.g. a French driver driving through Germany would hear German traffic information in French).
None is of any use in the US and you just ignore those icons on the screen. You can hide the TMC icon by turning TMC on in the Navi setup. But I haven't found a way to get rid of the TP icon.