The provincial governments are established, and their structure defined, by Chapter Six of the Constitution of South Africa.
The Premier appoints an Executive Council (a cabinet), consisting of members of the legislature, to administer the various departments of the provincial administration.
The powers of the provincial governments are circumscribed by the national constitution, which limits them to certain listed "functional areas".
The provincial executive does play a role in the selection of High Court judges, as the Premier of a province is ex officio a member of the Judicial Service Commission when it deals with matters relating to a High Court that sits in that province.
The only province that has adopted a constitution is the Western Cape; in doing so it chose to rename its legislature the Provincial Parliament.