It means that when you go looking for information you should use credible information, usually sites that aren’t Wikipedia
The European country that colonized Kenya was Great Britain.
The first president of Kenya when they became independent was Jomo Kenyatta.
Magna carta is one of the most important documents in history as it established the principle that everyone is subject to the law. It means "The great charter". It laid the foundations for Parliament and constitutional governments. Hope this answers the question.