A local government area (LGA) is an administrative division of a country that a local government is responsible for. The size of an LGA varies by country but it is generally a subdivision of a state, province, division, or territory.
The phrase is used as a generalised description in the United Kingdom to refer to a variety of political divisions such as boroughs, counties, unitary authorities and cities, all of which have a council or similar body exercising a degree of self-government. Each of the United Kingdom's four constituent countries has its own structure of local government, for example Northern Ireland has local districts; many parts of England have non-metropolitan counties consisting of rural districts; London and many other urban areas have boroughs; there are three islands councils off the coast of Scotland; while the rest of Scotland and all of Wales are divided into unitary authority counties, some of which are officially designated as cities. As such the term local government area is a convenient generic label referring to all of these authorities and the areas within their control.
The term is particularly common in Australia where it is synonymous with "municipality". Local government authorities across the country have similar functions and powers, but have different official designations in different states, and according to whether they are urban or rural. Most urban municipalities in all states are "cities". Many in Western Australia are officially "towns", even within the Perth metropolitan area. Many rural areas in Queensland, New South Wales, Victoria and Western Australia are "shires", while rural areas in South Australia have "district councils", and those in Tasmania officially use the title "municipality".
More information on the Wikipedia page [1]