This idiom or expression like sentence means:

I’m finished arguing.
I’m not arguing any more.
I’ve said all I’m going to say about it. I have nothing more to add.

Also, it is sometimes used to conclude that one is right.

A. Where were you when the robbery took place?
B. I don’t remember!!
A. You don’t remember? Well, I rest my case. (As you can see, I was right!)

Also see:
Case closed.

This idiom or expression like sentence means:

You’re gone.
You’re finished.
It’s the end for you.
It’s the end of the line for you.
I don’t want to see you (or work with you) any more.

A. Are you still upset with me, sir?
B. Yes. As a matter of fact, I want you to turn in your badge. You get off here!

This idiom or expression like sentence means:

We’re done.
It is finished.

It's a wrap, we can go home now.

This idiom or expression like phrase means:

The end of something.

When someone says “We haven’t heard the last word on immigration,” they mean something like “We haven’t seen the end of it. It’s not finished yet. There will be more discussions, disagreements, etc.”

Also see:
Have the last word.

This idiom or expression like sentence means:

Wait until it’s finished.
It’s not finished until I tell you.
It’s not finished until it’s actually finished.

A. The game is almost over. I guess we’ve lost again.
B. No, it’s not over until the fat lady sings.

Also:
It ain’t over until the fat lady sings.

This idiom or expression means:

Finished.
Really tired.