You do not have a link list with a handle set to custom-art-prints-for-home-decor, or you do and it's empty. Go ahead and create a link list called Custom Art Prints for Home Decor - Quality & Style on your Navigation page and populate that link list with links that point to collections, to see collections listed here. Make sure the link list also has a handle set to custom-art-prints-for-home-decor.