Directional, informational or safety signs. For a business or public utility, on-premises signs or notices for the direction, information or safety of the public to identify public parking areas, fire zones, entrances and exits and similar signs. They may be illuminated or nonilluminated, not exceeding four square feet per face, and, if freestanding, they shall not be more than six feet in height. Business names, symbols and personal names shall be allowed, but advertising messages are prohibited.