"That's it. She got her results" (Ça y est)

Question

HI there, long time fan, first time commenter.

I have no idea what 'that's it' is supposed to mean in this context? It isn't a phrase I would ever use unless used in the following scenarios:

"That's it! You've cracked the case." (When referring to a previous piece of information or clue or input).

"That's it. I've had enough."

"That's it. I've been looking for it everywhere" (here I would use 'that's the one' instead).

Could you please provide an alternative of what this is supposed to mean? As this translation feels awfully unnatural to me. Is this a specific phenomenon that can't really be translated or is situational? As I would never say "That's it. She finally got her results" in this way?

Cécile Janty-Davies · Accepted Answer

Bonjour Francis, 
In my opinion, the expression 'ça y est' is one of the most difficult to translate into English, as it depends on the context.
It's an exclamation used when something has finally been accomplished or completed, or when something you were waiting for has finally happened.
Mostly it will mean:

That's it!
There we go!
Done!

Depending on context, it can also mean:

We're done!
Finally!
Got it!
All set!

Hope this helps!