What was the significance of the reunification of germany in 1990?

It was a clear sign that the Cold War was coming to an end.

East Germany and West Germany were reunited into a single Germany under elections held in 1990, NOT in 1989.

Proved that the USSR and their Idea of Comunism Failed

the end of the cold war and the formation of the EU today

The Berlin wall was the greatest sign of communist oppression in the entire world at the time. There were families that had part of their family on one side of the wall and part of their family on the other side. The families weren't allowed to see each other. And if someone tried to cross the wall, they were shot dead.

East Germany's economy was bad. West Germany's economy was thriving. Ronald Reagan visited the wall in the 1980's and made an outright challenge to Gorbachev (the leader of Russia at the time). Reagan simply said "Mr. Gorbachev, bring down this wall!"

And Gorbachev did. Gorbachev also was the one that helped Russia move from a communist country to democratic elections. So Gorbachev deserves a lot of the credit. In fact, later he moved to the United States and lived in California I believe.

I grew up when the wall was in place. Seeing it come down was HUGE. That, the fall of Russia and the Arab spring were probably the biggest political forms up upheaval I've ever seen in my life.

It was completed in 1990, it really happened in 1989. It signifies the beginning of the end of the Cold War. The Soviet Union ceased to exists soon after.