When buying a rim many have different offsets as you well know, what i dont know is what offset actully means. Hate to sound stupid but when it say +40 or +45 what is it meaning. Also after that what is our stock offset.

Offset refers to how far the center line of the rim is from the actual mounting part that is flush with the brake rotor/drum. I believe OEM offset is 46mm. Not positive on that however.

Not really something to worry about too much until you are running 235/40/18s or something rather large (in which case you need an offset that will get the rim further out so it will not rub in sharp turns).

Check this link for more info.

http://www.vfaq.com/mods/macross/2Gfitment.html

So if im understanding correctly if I had an 0ffset of 50 or so the tire would actually be further under the car and if had an offset of say 30 it would actually stick out of the car a little more.

Yup.