It shows that each of the units shown with the content face are making (or at least has the ability to make) unhappy citizens content. i.e. they is acting as a military policemen. This will only happen in governments such as Monarchy, Despotism, Fascism and Communism. (Have I forgotten any?) The maximum number of MPs is dependant upon the which of these governments you are in.
It does not alter their ability to fight in any way.
Edit: I'm pretty confident that it does not make them happy. I'm possibly being pedantic but I can think of why this subtle difference could have an effect.
It does not alter their ability to fight in any way.
Edit: I'm pretty confident that it does not make them happy. I'm possibly being pedantic but I can think of why this subtle difference could have an effect.