The phrase "gold mules" refers to shoes that are made of gold or have a gold color. The word "mules" specifically describes a type of shoe that is open at the heel. Full definition
I chose to wear this forever 21 light blue floral kimono with a pair of high waisted raw - hem jeans, a simple white tank and my favorite gold mules (Yes, I'm aware I wear them all the time. (thenomisniche.com)
Plus, the dress gave me the excuse to wear my rose gold mules again (last seen here). (straightastyleblog.com)