A nation-state is a state in which an ample majority of its population shares the same cultural background and is conscious of this. An ideal scenario for a nation-state happens when the majority of the population, besides sharing the same cultural beliefs, also shares the same political beliefs.
The vast majority of countries in Latin America are nation-states, as the people who live in these countries have common religious beliefs as well as traditions. However, this is not the case in Europe, where there have been many civil wars, particularly in the eastern part, due to deep religious and cultural differences.