That’s a lot of food

Fruit and vegetable store
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Seller: What can I do for you, sir?
Boy: That’s a lot of food.
Seller: What was that you said?
Boy: I said, "that’s a lot of food".
Seller: Oh, yes we have a lot of food in this store.
What would you like? Fruit? Vegetables?

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Another example:

Boy: Oh. Now, the lights have come back on again.
Mom: Yes, because I replaced the fuses.
Boy: Why did you replace the fuses?
Mom: Because the old ones blew. When I turn on too many
electrical appliances, such as my hotplate, my toaster,
my electric kettle, and my refrigerator.
Boy: That's a lot of appliances.
Mom: Exactly. When I use too much electricity, it blows the
fuses.

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What does "That’s a lot of food" mean?

Does it mean "What a lot of food"?

What does "That’s a lot of appliances" mean?

Does it mean "What a lot of appliances"?

Thank you