如果你对某人说“I have (got) your back”意思就是无论是多么困难的情况下，你都会鼎力支持他们。

例句

Listen, you know I've got your back. If you want to make a complaint I'll support you. I saw exactly what happened and it wasn't your fault.

You know I love you. Whatever you decide to do, I've got your back.

请注意

当某人在没有得到别人同意或不知情的情况下做了有可能会损于他人的事情，这种行为就是“doing something behind someone's back 在别人的背后做事”。

例句

I can't believe you went behind my back and told my dad that I'd crashed his car. I wanted to do that myself. Now it looks like I was lying.

When I was young I never had any cool clothes. My friends used to laugh at me behind my back.