The word "antibacterial" generally refers to some sort of chemical substance that kills bacteria. Like antibacterial soap. Cicadas, which don't always have access to antibacterial soap (the insect market is woefully under served by household cleaning products), have evolved a way to kill bacteria that's built right into the structure of their wings.
Under an electron microscope, cicada wings are covered with forests of tiny nanopillars, smaller than bacteria. These are pillars, not spikes, with blunt tops as opposed pointy ones. When a bacterium comes in contact with the wing surface, it sticks to these nanopillars, which hold it up in some places but not in others. The bacterial membrane then sags into the spaces between the pillars, and if it sags enough, it'll rupture, killing the bacterium.
Think about it like one of those inflatable swimming pools: if you fill it with SpaghettiOs and then try to lift it from the sides, the unsupported bottom will eventually tear open and you know what happens next. Or, you can not think about that at all, and just watch this video:
This discovery is exciting because it should eventually be possible to replicate the cicada wing structure with synthetic materials and create a mass-producible antibacterial surface. Then we can stick that everywhere, like on public transportation and in bathrooms and Denny's restaurants — that sort of thing. If we wallpaper these places with cicada-wing nanomaterials that kill bacteria on contact, we won't have to waste time and money and the goodwill of Mother Earth with chemical cleaning agents, and surfaces will stay bacteria-free permanently.