There's a blurb on the page, but I'll try to say bit. The pages there are rendered from some structured data that has been collected to facilitate mapping businesses in OpenStreetMap. Mapping the brand to OSM tags makes it easier for new users (and everyone else) to figure out which tags make sense for given store.
It's real nice when mapping using street level imagery, any brand in the index can be quickly mapped just by searching on the name.
Tracking the wikidata items serves 2 purposes. The first is that wikidata is a decent place to go look for further information about the brands. The second is a bit of a trick of curation, the existence of a wikidata entry tends to imply that the brand exists.
There's some plans in the works to use icons from social media in OpenStreetMap editors to further reinforce that the correct brand has been tagged. That's one of the things that is useful to add to wikidata, Twitter handles and Facebook pages.
Maybe a better title: "Canonical common brand names for OpenStreetMap"