A 30.06 sign forbids people from carrying a concealed handgun into a property, in compliance with Section 30.06 of the Penal Code. On the other hand, a 30.07 sign created as per Section 30.07 of the Penal Code prohibits people from entering a property with an openly carried handgun. Properties often post both the signs to keep their premises gun-free.  You may find more information about these sections here.