Final answer:
Latvia is the Baltic Republic bordered by Estonia, Russia, Belarus, and Lithuania, which gained independence from the Soviet Union in 1991 and joined NATO and the EU in 2004.
Step-by-step explanation:
The country that is a Baltic Republic bordered by Estonia in the south, Russia in the east, Belarus in the southeast, and Lithuania in the south is Latvia.
Latvia, along with its fellow Baltic Republics of Estonia and Lithuania, declared independence from the Soviet Union in 1991 and has since transitioned to a market economy with a democratic government.
After this change, Latvia, Estonia, and Lithuania were welcomed into the North Atlantic Treaty Organization (NATO) and the European Union (EU) in 2004, further integrating them with Western Europe rather than their past association with Eastern Europe during the Soviet era.