Answer: The United Nations was replacing the former League of Nations formed after the end of the First World War. They were replacing the former League of Nations because countries weren't complying to the League of Nations rules they set up, and they did not care. The United Nations was formed to set peace in most of the countries of the world and make human rights laws better. Also for World War 2 not to repeat itself.
Step-by-step explanation:
I don't think it needs more explanations. If this is a homework of yours, try to rephrase it.