As you can see in Birdfly's examples, this is used to compare one thing to another. You do not need to agree that they are the same. The nat was like an elephant! These are called similes.

It's hard for me to explain how to use it.I just can list some examples:1、My work was like an addiction. That's why I've been able to do it for so long.2、She was like a narcissus trembling in the wind.That's all I can help.