I wrote"Скільки це коштує сало" and it marked it as incorrect because it is supposed to be"Скільки коштує це сало"
Indeed "Скільки це коштує сало" is incorrect, but you answered your own question.
"Це" describes "сало," so you have to move them together: "Скільки це сало коштує?"
This was what i wrote, but it is still considered wrong. is 'how much the lard costs?' less correct than 'how much costs the lard?' here?