Where in the world?
The flag of Portugal has a green field on the hoist side and a larger red field on the fly side with the national coat of arms where the two colors meet.

Portugal

Population: 10,305,564

Region: Europe

Subregion: Southern Europe

Capital: Lisbon

Top Level Domain: .pt

Currencies: Euro

Border countries

The flag of Spain has three horizontal stripes of red, yellow, and red with the national coat of arms on the yellow stripe.

Spain

Population: 47,351,567

Region: Europe

Capital: Madrid