Relations Between Union and States
(1) If two or more states' Legislatures resolve that Parliament should regulate a State List matter for them, Parliament may pass a law applying to those states - and any other state can later adopt that same law by its own resolution. (2) Such a Parliament Act can only be amended/repealed by Parliament, not by an individual state's own legislature, even for states where it applies.
This lets states voluntarily hand over law-making power on a specific subject to Parliament, when they want unified, centrally-legislated treatment of an issue rather than each state legislating separately - a cooperative, opt-in mechanism rather than a top-down central imposition.
This mechanism has historically been used for subjects where states wanted a single, uniform national law rather than a patchwork of different state laws - once passed, other states can simply adopt the same Parliament-made law for themselves rather than drafting their own separate legislation.