"Natural Wine" is a term bandied around. There really isnt a precise definition although one hardened group insists it means wine with no added acid (adding tartaric acid, the same acid as found naturally in grapes, is common in Australian wine making).
Not only does natural wine indicate lesser additives and a healthier product, it is a term that signifies an attitude by the wine maker - supposedly to be true to the flavour and condition of the grapes in the location. Hence it has become a marketing term and is often discussed by restaurant sommeliers.
Keep an open mind about natural wines - some are unpleasant and contain faults. Many are excellent. The term does indicate a small passionate producer and for many wine buyers, that is important.