The cold war showed the divide between capitalism and communism and overall showed how the world war divided. It even left every country vulnerable as if one nuke were ever to set off, the other country would counter-attack with their own nukes POSSIBLY causing an extinction event. This is called M.A.D or mutually assured destruction where if one country fires a nuke onto another, the other country will counter attack with nukes which will cause all-out destruction.
Overall, the main significance was the danger it posed to the 2 superpowers with completely opposing ideologies which dragged pretty much every other country with them. It even showed that war was no longer a possibility nowadays because if any of the superpowers were to go to war, nukes would be used to utterly destroy the other. So they had to avoid a direct war at all cost.
