Natural beauty is one with attractive features and looking attractive naturally without any makeup. It means your lips are beautiful without any lipstick or lip balm, your eyes are beautiful without any kajal or eye makeup, your face is shiny without any compact. Everybody has natural beauty.
Answer: when you don't change yourself for society. It is when someone is beautiful without makeup, fillers, botox, or plastic surgery. You were born with not only symmetrical features but big and full features that many find attractive.