What does the end of bipolarity mean?

End and disintegration of USSR.

The Berlin Wall, which had been built at the height of the Cold War and was its greatest symbol, was toppled by the people in 1989. This dramatic event was followed by an equally dramatic and historic chain of events that led to the collapse of the ‘second world’ and the end of the Cold War. At that time bipolarity was also ended and there was disintegration of the Soviet Union (USSR).