Policies have concrete effects for gameplay. Some increase your cities’ Production, while others generate more wealth, and still others help create a more effective military. There are no right or wrong policy choices in the game, and one policy may be better for a given circumstance than other, or better suit your personal playing style. Try them out and see.
There are 6 types of policies, each of which may be slotted into a corresponding slot in a given government. Slotting these individual policies will give you the benefits described and enhance your game.