This is a reference book about Belarusian/Slavic mythology. It consists of brief blurbs about various gods/demons/heroes/trees prominent in (predominantly pre-Christian) Belarusian myths and legends, arranged alphabetically, with illustrations in a rather wonky, but not entirely inappropriate, style. Some of the entries deal with entities well known to anyone who ever picked up a book of Slavic tales, others with less familiar topics, and others still sound so suspicious that I often cursed the author for not citing every claim they made.
While not a bad book, it's hard to see who would want to read it and how. It's obviously not something you would want to read cover to cover, but as a reference book the entries are too brief and too light to be particularly useful.