the end; closing; being done for
Polite noun for the end or conclusion of something; often used in the phrase おしまいにする (to finish/stop). The gloss 'being done for' refers to being ruined or finished in a negative sense.
See also: 仕舞い
That's the end of today's class.
It's all over now.
that's it; that's enough; that's all
Interjection used to declare that something is finished, enough, or settled; often said when stopping an activity or concluding a matter.
That's it! Playtime is over.
That's enough. Let's stop talking about that.
That's the end of class.
Let's put an end to this conversation.
If you give up here, it's all over.
I lost my wallet—I'm done for.