In science, the name for an animals that have black and white vision is ‘monochromat’. But dogs are actually ‘dichromats’.
Dichromat means that the animal can see two different colours (and a range of colours in between). They can mostly see blues and greens, but its hard to know exactly what a dog sees without asking it! And you probably won’t get a very sensible answer.
Humans are trichromats, we see in red, green, and blue. We can mix these colours to see all of the other ones because there is some overlap and our brains are very good at mixing information and giving us good vision. It is possible that dogs are the same!