A province is a geographic area, usually with some governance secondary to the governance of a central state or country. In many cases, a province is essentially the same as a state in many respects. The province may be run by a governor and may have some powers that are not decided by the country.
There are also times in which the therm province can also be used as merely an expression to define an area. For example, in France, anything outside of Paris would have been part of a province, hence the term provincial. Provinces in France now are likely to refer to regions of France rather than governmental structure.
A number of countries divide their area into provinces. Canada, for example, has provinces instead of states; it also has territories. Canada's ten provinces have more rights directly from the constitution, while the three territories get their power from the government. A territory has fewer "states rights" and must generally abide and not supersede the laws at the federal level.
As with state versus federal powers in the US, sometimes the rights of the province may be argued against the rights of the country. Depending on the country's constitution, any "residual powers" — those not specifically defined — may fall to the states or provinces, or to the central government. Which rights are residual and which are defined varies by country.
The checks and balances between the provincial and the federal government can and do create tensions. When certain powers are not defined for a province in the county's constitution, these residual powers can create conflict. In addition, there can be conflict between decisions made at a federal level and jurisdiction at the provincial level if the areas of power overlap.
Provinces are not exclusive to voting countries. The largest province in the world is in China, which is divided into 23 provinces, each led by a governor. The real power lies in the Committee belonging to the People's Republic of China. The governor of a province in China answers to the committee.
One of the exceptions to the rule in China is Taiwan, which is not administered by the People's Republic of China. It is the only province in China that is controlled by the Republic of China and solely administered by that republic instead of the central Chinese government.