Dylan Bennett of Youtube made these very informative and easy to understand guides to some of the more important terms in photography.
ISO (the light sensitivity of the sensor and what happens if you turn up ISO).
DoF ('Depth of Field' or how much of the image that is in focus).
F-stop (aka aperture size and those 'weird' f-numbers).
He did not make a video about shutter speed (yet) but you could read the Wikipedia article about different shutters for an in-depth knowledge about this important part of the camera.