There are plenty of free resources available on the market to learn data science, like e-books, articles, pdfs, online video tutorials, and so on. But I suggest you go with free online videos by experts for a better understanding of concepts because through e-books and articles you can't get clear idea of all the concepts. For that, I would like you to watch this video provided by Intellipaat -
This video helps you to learn various concepts of Data Science from scratch level. This video not just covers theoretical concepts but also some hands-on projects and case studies for your better understanding.