Alright, kiddo. So, you know how there are different religions in the world and people follow different beliefs? Well, in the United States, some people wanted to have prayers in schools according to their own religion.
But, school is a public place and the government has to be fair to everyone. So, they said that schools cannot have official prayers because it might make some students feel left out or uncomfortable.
However, students can still pray on their own or with friends during free time like recess or lunch. This way, students can practice their religion in their own way without disturbing others.
That's the ELI5 version of school prayer in the United States. Hope that helps!