The Treaty of Versailles had MANY damaging provisions in it. The entire idea was for Germany to accept full responsibility and blame for the massive destruction that the war had caused.
One of the most damaging provisions was Article 231, the “war guilt clause”, forcing Germany to pay tremendous war reparations to all countries affected by the war’s reach.
In essence, this dealt a devastating blow to Germany’s economy, causing them to print a ludicrous amount of money. This led to hyperinflation and the eventual collapse of the German economy. And obviously, this resulted in Adolf Hitler’s rise. He had been in WWI and was a extreme nationalist. He aimed to bring Germany back to its full military potential after another treaty provision severely limited Germany’s armed forces to 100,000 soldiers, virtually not submarines or airplanes, and only 6 battleships