By definition, the government of a society is the part of that society that (1) claims a rightful monopoly on the use of coercive force, (2) claims the right to make and impose rules on others, and (3) has the effective coercive power to enforce these claims. This is the standard definition of “government” in political philosophy.
Governments enforce their rules with violence or threats of violence. To illustrate this point, the philosopher Michael Huemer asks you to imagine you receive a speeding ticket for $100. When the government issues you a ticket, it thereby commands you to pay it $100. What happens if you do not pay? At first, the government will issue more commands. It will increase the fine and thus command you to pay more. It might eventually revoke your license. To revoke your license is to command you not to drive. Now, suppose you ignore all of these commands. You continue to drive as you please and you do not pay the fines. Eventually, the government will arrest and imprison you. It will command you to submit to the police. If you do not heed its command to submit, it will use violence to make you submit. If you continue to refuse its commands, it will tase you, beat you, or shoot you.