"Hereford Beef" is the same kind of thing as Safeway Stores "Ranchers Reserve" The only grades that are real have "USDA" before them. Examples, Prime, Choice, Select, Standard, etc. Everything else is made up by the Advertising Department.
The vast majority of beef cattle in the USA are the Hereford breed. Hereford are reddish colored with white faces.
Sometimes, they cross breed them with Angus cattle to produce smaller sized calves which are easier for cows to give birth their first time. Cross breed Herefords and Angus cattle are usually black body with white faces. One nickname for them is "Black Baldy"