It's a limited release, they only pressed 700 copies. It's intended to make the copies more valuable (similar to limited releases of prints for visual artists).
It's a bit ambiguous butAccording to this site, it looks like there might be more copieswere other releases of the recordalbum, but only 700 of the gray-and-black swirl limited edition vinyl.
This site specializes in limited releases, you can compare. Or, if you share the name some of this album, it might be possible to look it up and see if it appears in that or other registriesthe others they have listed there.