Zinc oxide has antibacterial and deodorizing properties. For this reason it is employed in medical applications such as in baby powder and creams to treat conditions such as diaper rash, other skin irritations and even dandruff. Due to its reflective properties it is also used in sunblocks and can often be seen on the nose and lips of lifeguards at the beach.
Non nano Zinc Oxide means that the particles aren’t small enough to penetrate the skin. This is safer for your body.
For more info on Non Nano feel free to check out the EWG website.