“不对”的意思是不正确，或者是有什么地方不太好、和平常不一样。

"不对" means incorrect, or that something is not quite right or different from usual.

我们常常用它来说别人说错了，也可以说“这里有点不对”。

We often use it to say someone is wrong, and can also say "这里有点不对" (there is something a bit off here).