As a City Life Civilian, you are taking on a role (in the sense an actor has a role) and enacting or playing that character.
Mature behaviour and language will be dictated by the situation you are involved in. Be aware if your are under the minimum age to play ARMA 3 you may be subjected to adult language.
If you have a weapon on display the Police can only assume you intend to use it to cause death or serious injury so expect to be met with lethal force. You have a holster, use it.
If you are running around towns with no other intent than to kill, then we will assume you no longer want to play City Life and could face a ban. Gun fights happen, and we understand that, however, keep in mind that normal cities are not warzones, and we are trying to treat this game as a real life simulation.
We are not expecting you to all be saints, if you don't do illegal things, then the Police won't have anything to do, but don't go too far.