Pacification is an attempt to create or maintain peace. That can mean appeasing a hostile country through diplomacy or even just by settling an argument.
A pacifist is someone who is against fighting and wars. That can help you remember that pacification is a means — usually carried out by a government — to keep the peace or end a conflict. If two countries are having a war of words that could escalate, one country could use foreign aid (money) as a means of pacification. If a country is battling a revolution from within, stopping the insurgency can also be called pacification.