Cats use their front paws and toes to touch something, grab or push the toy or to clean themselves. Their back paws and toes are there to help them while running around and jumping on high surfaces.
This has to do with genetics. Polydactyl cats can be seen all over the world, but they’re mostly seen in Canada and the east coast in North America. There is no need for a special care with these cats; just make sure to trim their nails regularly.