Effective altruism is a movement that uses science to help people make more ethical choices about how they spend their time and money.
If you would like to read a book about the subject, I recommend William MacAskill's Doing Good Better.
If you'd like to watch an 18 minute talk on the subject, I recommend Peter Singer's TED talk. https://www.youtube.com/watch?v=Diuv3XZQXyc
If you would like a charity recommendation for helping human
beings, I recommend the The
Against Malaria Foundation.
If you are interested in animal welfare, a very effective organization is The Humane League.
These charities are highly rated on charity evaluator websites such as GiveWell and Animal Charity Evaluators.
If you are interested in protecting the environment, I recommend Cool Earth. If you are unsure, I have reasons to believe that helping human beings, all things considered does the most good. My argument for this will appear in my next book.