Places the title, price, icons etc in a transparent container over the product image (Affects all product loop locations, but not the list view.). In order for the product meta to be fully transparent you have to set the Product meta with background option below, to 'No'.
If you want the meta to be completely transparent set the Product meta with background option, to 'No'. In any other case, you can set the background color for the product meta, so you can enhance the visibility of the text over the product image.