What is C/P

and how does it works

if u know give me a tutorial :3 pls

C/P just stands for Copy/Paste. For texturing, C/P would just mean that they copied the texture picture from somewhere and shaped it up to look good on the texture. It means they didn't draw it themselves, it's not hand drawn. C/P artwork is cheaper than hand drawn artwork.

If you make a texture or art that is C/P, you are required to post the reference picture of the art. If you have any more questions or if I didn't answer them just ask.

C/P isn't actually worse or cheaper. Some C/P sets are valued at really high prices, and not always by the artist.
One set Internet made was C/P, he sold it for 10k. Later people offered to buy it at ridiculously high prices. As well, FlyingMonk made loads of C/P sets, and sold them all for a price that was usually 200k+ at minimum.
It's just looked down upon, since it doesn't take as much skill and isn't really hard. It is far harder to make something amazing by hand, then it is to copy a picture.