An Act to grant certain duties, to alter other duties, and to amend the law relating to the National Debt and the Public Revenue, and to make further provision in connection with finance.
In the UK, the Chancellor delivers an annual Budget speech outlining changes in spending, tax and duty. The respective year's Finance Act is the mechanism to enact the changes.
The rules governing the various taxation methods are contained within the relevant taxation acts. (For instance Capital Gains Tax Legislation is contained within Taxation of Chargeable Gains Act 1992). The Finance Act details amendments to be made to each one of these Acts.