"His sisters read a book."
Translation:उसकी बहनें किताब पढ़ती हैं।
Why is this correct? I thought translating उसकी बहनें किताब पढ़ती हैं would give "His sisters read book", which doesn't make sense. I thought the correct way of saying it would be उसकी बहनें एक किताब पढ़ती हैं. So far, in all other cases before this Duolingo always specified if the object was singular by putting एक before the object.
उसकी बहनें किताब पढ़ती हैं would translate to either 'His sisters read a book' or 'His sisters read the book'.
Hindi does not have a definite article and the word for 'one', एक serves as the indefinite article. However, in practice, you can drop the एक and the definiteness is inferred from context.
So, 'His sisters read a book' can be translated as both 'उसकी बहनें एक किताब पढ़ती हैं' and 'उसकी बहनें किताब पढ़ती हैं।'.
Also, the plural of किताब is किताबें so there is no confusion that we are talking about a single book.