Where in the world?
The flag of Belarus has a red field with a green horizontal stripe at the bottom and a white and red ornamental pattern on the hoist side.

Belarus

Белару́сь

Population: 9,398,861

Region: Europe

Subregion: Eastern Europe

Capital: Minsk

Top Level Domain: .by

Currencies: New Belarusian ruble

Border countries

The flag of Latvia has a carmine red field with a white horizontal stripe in the middle.

Latvia

Population: 1,901,548

Region: Europe

Capital: Riga
The flag of Lithuania has three horizontal stripes of yellow, green, and red.

Lithuania

Population: 2,794,700

Region: Europe

Capital: Vilnius
The flag of Poland has two horizontal stripes of equal width, white on the top and red on the bottom.

Poland

Population: 37,950,802

Region: Europe

Capital: Warsaw
The flag of Russia has three horizontal stripes of white, blue, and red.

Russian Federation

Population: 144,104,080

Region: Europe

Capital: Moscow
The flag of Ukraine has two horizontal bands of blue and yellow.

Ukraine

Population: 44,134,693

Region: Europe

Capital: Kyiv