Prerogative powers

The royal prerogative is a body of customary authority, privilege, and immunity, recognized in common law and, sometimes, in civil law jurisdictions possessing a monarchy, as belonging to the sovereign alone. It is the means by which some of the executive powers of government, possessed by and vested in a monarch with regard to the process of governance of the state, are carried out.

In most Constitutional monarchies individual prerogatives can be abolished by Parliament, although in the United Kingdom the royal prerogative is devolved to the head of the government.

Though some republican heads of state also possess similar powers, they are not necessarily exactly the same as in every jurisdiction, and may have a number of fundamental differences both in the method of enforcement and extent of the powers available to the state's Chief Executive.

In Britain, while prerogative powers were originally exercised by the monarch acting alone, without an observed requirement for parliamentary consent (after Magna Carta), since the accession of the House of Hanover these powers have been generally exercised on the advice of the Prime Minister or the Cabinet, who in turn is accountable to Parliament, exclusively so, except in matters of the Royal Family, since at least the time of William IV.

Typically in liberal democracies that are constitutional monarchies as well as nation states, such as those of Denmark, Japan or Sweden, the royal prerogative serves as a prescribed ceremonial function of the state power.

...
Wikipedia