If you buy FSD you will get the HW3 computer swapped into your car if the car doesn't ALREADY HAVE IT (which basically 0 model 3s have it right now- but new ones being delivered shortly will) starting in a few months.
If you do not buy FSD, and have a car that lacks the HW3 computer, you won't get the HW3 computer- but also won't need it anyway since it's only needed for FSD.
The reason this question is funny is it didn't used to mention the computer- and people were mad about it, saying they couldn't trust Tesla to keep their word (despite a dozen or more public statements on the topic) that FSD buyers would get the new computer UNLESS THEY MENTIONED IT ON THE ORDER PAGE.
I pointed out they don't do that because to those who know WTF the computer is- they already have been the dozen other public statements so they don't need it....and for those who aren't sure what the computer is- it will just confused them.
So they added the wording anyway- and here we are with doing so leaving someone confused just as I said we would be