Written and approved laws. Also known as statutes, acts or lex scripta.
In constitutional law, one would talk of the "power to legislate" or the legislative branch of government referring to the power of political bodies (eg: house of assembly, Congress, Parliament) to write the laws of the land.
Legislation takes shape when a proposed law is set out before a formal assembly, such as the House of Representatives or Parliament. At that time, the proposal is not law yet and it is merely a bill. Once approved in accordance with the constitutional requirements of the particular parliamentary assembly, it is then legislation, a fully enforceable law.