It’s a biblical story that involved man thinking they can reach heaven if they can build a tower high enough. According to the story, God became infuriated by this and destroyed (or griefed :P) the tower and made everybody speak different languages, which is supposed to explain why we have over 5,000 languages today.
TL;DR: Humans made tower that later became griefed by God for trying to get his intel and caused everybody to speak different languages.