Meaning: There is no more to be said or done; the matter is finished.
"Father said he wouldn't buy you a new car, and that's that." - I won't discuss it any longer.
"I've finished packing all the boxes, and that's that." - The task of packing the boxes is now finished.
"I'm not going, and that's that!." - I won't discuss it any longer.
"I called Tom and told him our relationship is over, and that takes care of that."
That's that. I hope you understand today's expression. Give us your own example sentences:
