Anything governmental relates to a government, which is a political entity that runs a city, state, or country. If you work for the President, you have a governmental job.
The government is the body that runs (governs) a country. Add the –al ending, which means “related to,” and governmental describes anyone or anything related to a government. It’s like the words continental and environmental. The FBI, FDA, and IRS are governmental agencies. A governmental internship might involve working for a senator. The executive, legislative, and judicial branches could be called the three governmental branches in the U.S.