It's often used to form words describing a type of government or system of rule, such as:
* Democracy: Rule by the people
* Autocracy: Rule by one person with absolute power
* Theocracy: Rule by religious leaders
* Bureaucracy: Rule by officials or administrators
* Technocracy: Rule by technical experts
So, while "cracy" doesn't have a meaning on its own, it helps create words that indicate a specific type of power structure.