A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed.
What it says and really means is that individuals' rights to keep and use weapons shall not be taken away or reduced because the security of a FREE state depends on the government's military powers being balanced by a citizenry that is capable of defending itself from a government that has become oppressive, like the one that the Revolution defeated.