Program mode. It's a semi-automatic setting whereby the camera will choose the aperture and shutter mode to achieve the correct exposure.
The difference between P and Auto is that in P you have the option to shift the settings. For example, say your camera indicated a correct exposure would be achieved with F/4 and 1/500s, you could then shift the values in one click/turn to F/8 1/250s or any other combination, maintaining the correct exposure, but giving you a greater level of control.