English requires you to include an article with the noun 'book' to indicate definiteness. This can either be 'the'(definite article) which indicates that you are talking about a particular book or 'a' (indefinite article) which means you may be talking about any book.
Hindi is laxer with articles. There is no definite article and the word for one (ek) is used as the indefinite article. Absence of 'ek' usually indicates definiteness but may also stand for indefiniteness depending on context.
So, you can translate मुझसे किताब मत लो as either "Do not take the book from me" or "Do not take a book from me".