what does fortitude, reflex, and will do? and what does saves mean?
Fortitude, Reflex, and Will are the Saves (also called Saving Throws). This game uses the d20 system, so the calculations are based on a 20-sided dice. Reflex, Will, and Fortitude serve as the numbers that determine your character's ability to ward off enemy attacks of a certain type. Reflex is based on Dexterity, Fortitude is based on Constitution, and Will is based on Wisdom.
and what does, when armor says something like, max dexterity plus 8 or something?
That means that your Dexterity bonus will be cut off if it exceeds what the armor allows. For every even number past 10 (12, 14, 16, etc), you get a Dexterity bonus of +1 (so 16 would be +3). If your Dexterity bonus exceeds what your armor allows, you do not receive the benefits of the bonus.