I think the explanation is crazy.
The numbers indicate approximately the highest oxidation number of the elements in that group, and so indicate similar chemistry with other elements with the same numeral. The number proceeds in a linearly increasing fashion for the most part, once on the left of the table, and once on the right
So, since the two formats agree, Group 8, the "Iron Family" either VIIIA or VIIIB depending, have +8 oxidation numbers or oxidation states? Well, ruthenium does, but iron doesn't.