Not every store sells every language. KDP, for one, prints Polish and Ukrainian books but doesn't sell them as Kindle ebooks, and doesn't publish Russian at all. The guide lists, for each format of this edition, the stores that take it in its language, with a kit for each store the studio knows.
Some national stores have no sign-up for self-publishers; the guide says how authors reach them instead.
When the book says what it is (a novel, poetry, a memoir and so on, on the book's page), the guide marks the stores that suit books like it, and says why.