what exactly is kc reg?

up until now i have only ever had rescue dogs, but recently bought a white german shepherd pup from a private seller. i dont really know much about dog breeding and all that comes with it- the breeder unfortunately passed away when the pups were born and his son was left with all the dogs but no space or cash to look after them. the parents went to the rspca and he sold the puppies.

i have a pedigree form but he said the puppies wernt kc reg because the dad was but the mom wasnt.

i only want the dog as a pet- i have no intention of breeding whatsoever, we just needed a companion for our border collie.

does this matter? im not even sure what kc reg means lol