I don't think I'd ever use the sentence "What does the book contain?" "What is the book about?" would typically prompt the full response - genre and detail. If that's not true of Swedish, though, the response makes sense - now I just have to remember it! (And it's not WRONG in English - just odd.)
It would help to have alternate translations to English: Wiktionary: innehålla → encompass, enclose, contain innehålla → include, embody, contain, hold, admit, comprise
The Table of Contents page lists what the book contains.
However, the suggestion of a book hollowed out for a gun and given to a prisoner is a humorous impression from the translation, "What does the book contain?" Duo provides lessons that get us laughing!
"What is the book about?" can become part of what a book contains:
The book about Mesopotamia contains one chapter about the prehistory, a few chapters about the earliest civilizations, several more about the influence of various invaders, and then four chapters about the transition to the current state of this region.
I think if I would wanna know that I would just say : "vad finns i den där boken ?" or something... like literally "what is there"...
My native language is Dutch and there we would ask what the "inhoud" (=contents) of a book is/are. To that question i would definitely reply with a description of the story or topic and ...
"Inhoud" is very much related to "Innehåller" (both Dutch and Swedish are Germanic languages) so I would expect this to translate to "What's the book about" first ! And then maybe to "what does the book contain" if you'd want to translate it very literally...
Well, I wouldn't ever use this sentence either, however Andy Dufrense probably said the same thing until he arrived at Shawshank Penitentiary. After many years of disregarding the sentence, he was asked...'hey Andy! whats does your book contain?' to which he replied.. 'a very useful rock hammer'... so learn it just in case :-)
It's sort of a murky area, I think. It is important to have proper spelling and grammar, since sometimes two words will be different by only one letter. (Finnish can be a nightmare sometimes, because certain words in the wrong case are considered vulgar). On the other hand, if they were consistent, I think there would be fewer problems. However, some exercises in the same course will accept multiple typos while others will mark you wrong for the same thing. I am unsure if it is set by the individual contributors, which might explain why it is inconsistent. Worst is when you are using a stupid touch screen phone and you bump a letter without noticing.