Clicking on this claim it states that dogs have two types of cones. They are only able to discern blue and yellow. It states that dogs are unable to see the entire spectrum of color that humans do. For example, the color red appears a dark brownish-red and purple looks like same as blue to them.
Some say dogs can only see black and white. According to the American Kennel Club, the largest not-for-profit all-breed registry, with more than 5,000 licensed members, dogs are more related to colorblind. Dogs and some color-blind people are missing red and green cones in their retina. They also claim that dogs can make out yellow and blue and combinations of that color. It is not as bright as human vision. It is more faint.
https://www.akc.org/expert-advice/health/can-dogs-see-color/
In conclusion this claim is exaggerated/misleading. Dogs do not just see black and white and they can see some color. They cannot see the same color that humans can but they can see color to an extent.