What is bill?
bill meaning Formally introduced legislation. Most legislative proposals are in the form of bills and are designated as H.R. (House of Representatives) or S. (Senate), depending on the House in which they are introduced. They are numbered in the order in which they are introduced during each Congress. Public Bills deal with general questions and become Public Laws, or Acts, if they approved by Congress and signed by the President. Private Bills deal with individual matters such as claims against the Federal Government, immigration and naturalization cases, land titles, and so on, and become Private Laws if approved and signed.
reference: Ben’s Guide U.S. Government – Glossary