I have looked up the words “Brand” or “Brands” in the PO files of the theme (Woodmart) and Woocommerce plugin but it does not yield results that can alter the appearance of the words “Brand” or “Brands” on the front end. While I suspect that the static “Brand” or “Brands” strings should be within the standard Woocommerce plugin and PO file. Not sure though, and it seems to be a new feature as I haven’t noticed the Brands option under Product before.