I need to know what does "specify law providing each exemption" mean?
You need a lawyer or at the very least a lot of studying. The studying should be done at a local Trial Court Library and not on the internet.
Chapter 7 bankruptcy is a liquidation proceeding, this means that the case trustee will collect all your assets, sell them, and pay off your debts with the cash to the extent possible.
However, Congress does not want to leave you homeless and naked so they have carved out certain exemptions from liquidation. Schedule C list these exemption and you must tell the Court and the Trustee how your property is exempt from being liquidated. In correctly or not exempting property could literally mean losing a home, car, or other assets.
You should really consider hiring a lawyer, most offer a free consultation and payment plans. If you are really going to do it you self, please read a book on the topic first. Nolo offer several good publications as well as the National Consumer Law Center.