Where in the world?
The flag of Uruguay has nine horizontal stripes of white and blue with a white square in the top left corner containing a yellow sun with a face.

Uruguay

Population: 3,473,727

Region: Americas

Subregion: South America

Capital: Montevideo

Top Level Domain: .uy

Currencies: Uruguayan peso

Border countries

The flag of Argentina has three horizontal bands of light blue, white, and light blue, with a yellow sun in the center of the white band.

Argentina

Population: 45,376,763

Region: Americas

Capital: Buenos Aires
The flag of Brazil has a green field with a yellow diamond and a blue globe with stars in the center.

Brazil

Population: 212,559,409

Region: Americas

Capital: Brasília