Freenet is not a place or a website. This is literally the same as asking "so how does the internet prevent spreading of slander or libel?", or as another comm

Freenet is not a place or a website. This is literally the same as asking "so how does the internet prevent spreading of slander or libel?", or as another commenter pointed out, asking how the global telephone system does the same. The question has no answer because the question doesn't make sense. It's a question that shows a fundamental lack of understanding.