The next section is really interesting. Colour Dynamics allow you to change the way colours work in your brush. To see this effect I have set the brush colour to red.
(Before colour Dynamics)
Hue jitter does just that, it varies the hue of the brush along the stroke. So when this is set low you will see a range of colours from yellows to reds, but if set to 100% you will see a whole range of colours from all hues.
Saturation jitter varies the saturation of the brush. So some spots of colour will be desaturated while others will be bright and vivid.