A bullet is the small metal piece that is shot out of a gun, and dodge means to move so that you escape something.
Bullet是从枪里射出的小金属片，dodge的意思是移动以逃离一些东西。
It's used generally to mean avoiding any situation that turns out to be disastrous or very harmful.
它通常用来指避免任何灾难性或非常有害的情况。
Let me give you an example -a woman was dating a man who started acting controlling and abusive, doing things like preventing her from having male friends, and grabbing her by the hair when he was angry. Fortunately, she broke up with the guy and moved to another city, so he is no longer in her life. You could say:
让我给你举个例子——一个女人和一个男人约会，这个男人开始控制和虐待她，做一些事情，比如阻止她交男性朋友，当他生气的时候抓住她的头发。幸运的是，她和那个男人分手了，搬到了另一个城市，所以他不在她的生活中了。你就可以说：
She dodged a bullet because she avoided marrying with someone who probably would have abused her.
她躲过了一劫，因为她没有和一个可能虐待她的人结婚。
