A minister is a politician, who is a member of the government. A minister is the head of specific department of the government. He or she executes laws and oversees this department. Most ministers have a ministry. A cabinet has several ministers for the several departments. How much ministers a country or area has depends per nation. In some nations, the head of government is also a minister. His title is Prime Minister (PM), first minister, premier, chancellor, etc.
In the United Kingdom, a minister is a part of the legislature (parliament) as well as the executive (cabinet). In other countries, a minister is only a member of the executive, due to the separation of powers. This is the case in Belgium, the Netherlands and Slovenia. In most countries, a minister can also make laws and sent them to the parliament.
There are different kinds of ministers. For example, there is the agriculture minister, the culture minister, the defense minister, the education minister, the finance minister, the foreign minister, the health minister and the justice minister. They're named after the department of which they're the head. The ministry they work for has the same name. Some minister, mostly with smaller jobs, have no ministry. They're called a minister without portfolio and they house in another ministry. Some countries have made some ministers into one. The Netherlands has for example a minister for culture, education and science (one person, one ministry). This is cheaper. Other countries, have special ministers for certain areas, like the UK for Scotland, Wales and Northern Ireland, or for special causes, like the UK for the Brexit.