If you have been following world news at all over the last two and half years, you have likely heard about the referendum that the United Kingdom voted for in 2016 to leave the European Union. Even though it has been a big news story it may not be easy to understand. Thankfully, there is a video by CGP Grey to explain the issue with why an agreement cannot be made easily.
There is also a footnote video that adds a bit more information. Both of the videos are worth watching to learn a bit about the struggles that the United Kingdom is having.