Answer:
A federation.
Step-by-step explanation:
A federation is a union of self-governing provinces under a central federal government. Each province or region retains some power over their internal affairs, they do not have, however, any say in the country's foreign policies.
Mexico is a federation compromising 31 states similar in structure to the US states. Mexico also has a special federal entity, Mexico City, which is the country's capital city.
The population of Mexico is about 120 million, it is the most populous Spanish speaking country in the world. It is also the 13th largest independent state in the world.