The phrase "empty storefronts" refers to shops or stores that have no businesses occupying them. They are empty and not being used to sell things to customers. Full definition
A tenured professor at UCLA, she's behind the sly plywood - patterned curtains installed in empty storefront windows throughout the city (a West of Rome Public Art project — see «Emi Fontana»). (lamag.com)
It's been a year, and boarding up empty storefronts with nicely finished plywood does not seem the way forward. (hudsonvalleyone.com)
Vancouver radio station News 1130 confirmed these observations in a recent broadcast, when the it stated that «there are also plenty of empty storefronts along otherwise bustling corridors.» (moneysense.ca)