First Person View (FPV) flying is when you fly your radio aircraft using a wireless video feed and view it from the pilot's perspective using a FPV monitor or video goggles. It's the closest thing to flying without actually flying!
FPV flying not only gives a unique perspective on flying your RC aircraft (with some spectacular views) but also allows you to learn some new things in electronics and radio theory. Things like antenna/transmitter gain, antenna polarisation, radiation patterns, radio frequencies, wavelengths. FPV pilots are always learning about the best methods to get the pest possible signal back to the ground.