This might be a loaded question, but the fact is that I never learned who Che Guevara was but still I see him being mentioned everywhere, from people who idolize him and from people who demonize him. What exactly did he do in a historical sense? What was he known for? What did he contribute to? Why some people love him so much and yet a lot of people hate him?
Here is a popular thread with a similar question that may help you: https://www.reddit.com/r/AskHistorians/comments/2vemcp/che_guevara_is_a_hero_to_some_and_a_villain_to/