I don't know where you studied law but prostitution is legal in India. Prostitutes can practise their trade privately but cannot legally solicit customers in public. As long as it is done individually and voluntarily, a woman can use her body in exchange for material benefit. In particular, the law forbids a sex worker to carry on her profession within 200 yards of a public place.
A number of related activities including soliciting in a public place, kerb crawling, owning or managing a brothel, prostitution in a hotel, child prostitution, pimping and pandering are illegal.