So by now if you’ve been following this site you should be familiar with the three most popular exposure modes: Shutter Priority, Aperture, and Manual. One of the less talked about and consequently less known about modes is the Program Mode. That’s the P on your control dial.
The simplest way to remember this is that it’s partly automatic. You can adjust most settings but your exposure will be adjusted by the camera. If you’d like to adjust your aperture so that your depth of field (low f-number) is blurry the camera will automatically compensate by adjusting the shutter speed and conversely you can adjust the shutter speed to catch fast-moving objects and the camera will adjust your aperture accordingly. You can control your ISO settings, flash, and all other settings but the camera will make sure your exposure is set up correctly. So as you adjust your shutter speed or aperture the camera will automatically monitor your exposure and make sure that it remains the same, giving you a little creative room to work without the room for error.
As with anything, take your camera out and adjust your dial to P to try it out. Good luck.