I read that a country is a distinct national entity in political geography
Did you? That sounds about right. There are many countries in the world.
Yes, it can be an indepent sovereign state or one that is occupied by another state as a non-sovereign state
Do you know what the most advanced countries in the world are?
is subject to the independent exercise of legal jurisdiction. There is no hard and fast definition of what regions are countries and which are not.
"Countries" can refer both to sovereign states and to other political entities, while other times it can refer only to states. For example, the "CIA World Factbook" uses the word in its "Country name" field to refer to "a wide variety of dependencies, areas of special sovereignty, uninhabited islands, and other entities in addition to the traditional countries or
Country
A country is a region that is identified as a distinct entity in political geography. 
A country may be an independent sovereign state or part of a larger state, as a non-sovereign or formerly sovereign political division, or a geographic region associated with sets of previously independent or differently associated people with distinct political characteristics. Regardless of the physical geography, in the modern internationally accepted legal definition as defined by the League of Nations in 1937 and reaffirmed by the United Nations in 1945, a resident of a country