Council of the European Union
Its members are the government ministers of the member countries who are responsible for the law that is being discussed. As an example, suppose the law is going to be about farming, then the Agriculture Ministers are the Council for that day.
As well as making laws, they can meet to discuss their problems. For example, the European Union does not decide on tax - each country decides on its own tax. But the Finance Ministers meet anyway because sometimes they can help each other catch people who do not want to pay tax at all.
The Council is called different things in different countries, according to the language they speak. In (French it is Le Conseil de l'Union Européenne, in German it is Rat der Europäischen Union, in Czech it is Rada Evropské unie.
A simple way of putting it, is that The 'Council of the Europeon Union' is helped by most countries in the world and it is very important.