No, Lisbon [Lisboa] isn't a country. Instead, it's the most famous city in Portugal. It's the country's capital city and busiest seaport. It's located in western Portugal at the point where the Tagus River flows into the Atlantic.
Lisbon was already a 1,000-year-old town at the time of Roman rule in 205 BC. It was captured by the Moors in the eighth century. In 1147 it was reconquered for Christians under Afonso Henriques [July 25, 1009 - December 6, 1185].
Lisbon is the major cultural, economic and political center of Portugal.