Article 5: This can be compared with a rule within your neighborhood watch group stating if one house gets attacked, everyone responds. Article 5 declares that an armed attack against one member is considered an attack against all members.
Cold War: A period of geopolitical tension between powers in Eastern Bloc (Soviet Union & its satellite states) & powers in Western Bloc (US & its NATO allies). Like two rival gangs in a city, they never directly fought each other but had intense economic and political rivalry.
Warsaw Pact: This is like the rival neighborhood watch group to NATO during the Cold War. It was a collective defense treaty signed in Warsaw among the Soviet Union and seven satellite states of Central and Eastern Europe.