Does it mean it's a book about the English language, a book made in England or both?
It would mean it's a book by an author either from England or residing in England. It could also be a book that's printed in England, but that would be a very rare use of phrase.
could it also mean "a book in english"? e.g. a novel written by a swedish author, but translated into english?
Oh yeah, that too, but you'd be more likely to be a bit more explicite - e.g. det är en bok på engelska.
When should we use "Engelska" and when to use "Engelsk"?
For the adjective engelsk, engelska is the definite and the plural form, and engelsk is the indefinite en-word form.
Also, engelska can mean "English woman" as well.
Do note that unlike in English, we don't capitalise the first letter.
Thank you .. Is this correct saying "Den engelska kvinna" for "The English woman" ?
Close! It's Den engelska kvinnan, since the noun also needs to be in the definite.
Oh yes. Tack för svaret !!!