How to hang a canvas art using these nails?
Stick to the screws, and buy something appropriate to your wall-type at the hardware store to hang from.
The serrated bits are a form of picture hanger that normally mounts on the wooden frame (top center, usually just one, the serrations allow you to move it on a nail or screw until it hangs straight. If you use more than one, you have to get the things in the wall exactly right for the art to hang straight, as then there's no adjusting that way.)