"A thing about the economy is economic."
Translation:경제에 대한 것은 경제적이에요.
Maybe what you mean is "The thing about the economy is that it's economic" which is still a strange sentence, but its better than the original.
Based on the Korean, they don't use "about" in that way. I think it's more basic: "Something related to the economy is economic" as in economic ideas, not efficient.
I get why they would make a sentence like this, but translating it to English makes it a bit of a stretch to learn what the grammar is here.