The Small Council is a small group of advisers who aid the Lord of the Seven Kingdoms, the monarch on the Iron Throne, on matters of policy and their areas of expertise.

The small council traditionally consists of seven permanent members:

🔹Hand of the King, the chief advisor of the king and the second-most powerful man in the realm.
🔹Grand Maester, a representative from the Citadel who advises the king on any matter concerning governance.
🔹Master of coin, head of the treasury and finances of the kingdom.
🔹Master of laws, an expert in the laws of the realm.
🔹Master of ships, commander of the royal fleet.
🔹Master of whisperers, the spymaster and gatherer of information.
🔹Lord Commander of the Kingsguard, leader of the Kingsguard.

Councillors can be appointed by the king or a regent. Regents and Protectors of the Realm can participate in the small council meetings, and the council may include additional members as advisors. Some queens consorts also attend the council meetings.

The council is headed by the king, the only one who can make the council's decisions into law. If the monarch has not yet reached the age of majority, the small council can consent if they agree with the king's decisions. The Hand can also draft laws for the king. Once he reaches the age of majority, the king can appoint and dismiss councillors as he wills.

The small council can be entrusted with handling the day-to-day governance of the kingdom, especially by monarchs uninterested in minutiae. Councillors may be called 'Lords' even if they are not members of the nobility. Although their allegiance should be to the monarch, councillors' loyalty may be divided by faction or region of origin.

The small council meets privately in their council chambers in the Red Keep. When the king is not in attendance, the Hand may sit in the king's place at the head of the council table. A knight of the Kingsguard stands guard outside the chamber. There is also a table for the small council situated at the base of the Iron Throne in the Great Hall of the castle.

Source: Asoiaf wiki