She asks if he's done a lot count recently, and rather than answer
What is the meaning of the Marge words?
I specifically didn't understand "lot count" in the sentence.
Jerry Lundegaard is a car salesman. He works at a used car lot. "To do a lot count" means "to count all the cars in the used car lot". It's a similar expression to the more general "to do inventory".
I don't want to spoil the movie for you, in case you haven't seen it, but this is basically a major plot point that incriminates him.