Where in the world?
The flag of French Guiana has a green and yellow diagonal bicolor with a red five-pointed star in the center.

French Guiana

Guyane française

Population: 254,541

Region: Americas

Subregion: South America

Capital: Cayenne

Top Level Domain: .gf

Currencies: Euro

Border countries

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
The flag of Suriname has five horizontal stripes of green, white, red, white, and green with a yellow five-pointed star in the center.

Suriname

Population: 586,634

Region: Americas

Capital: Paramaribo