Complex sentence: The central district of the Upper Silesian Metropolitan Union-it is a metropolis with the population of 2 million people and is located in the Silesian Highlands, on the Brynica river (tributary of the Vistula).
Split into simpler sentences: The central district of the Upper Silesian Metropolitan Union-metropolis with the population of 2 millions. Located in the Silesian Highlands, on the Brynica river (tributary of the Vistula).