Yaesu System Fusion radios (at least the higher end ones) have a built-in GPS and APRS modem. Any VHF radio can be made to beacon on APRS with an external GPS receiver and a APRS controller.APRS allows you to beacon your position so that others can see where you are. A GPS receiver provides your position so it can be included in the beacon.
Yaesu System Fusion and D-STAR also have the capability to include your position in the data stream when you transmit. Again, a GPS receiver is necessary to provide your position.