Giles Corey only asks Rev. Hale one real question in Act I. He asks it in a couple of different ways, but it is essentially the same question every time. What Corey asks Hale is what it means that Corey's wife has been reading "strange books." He says he has always wanted to ask a learned man that question.
I suppose it shows his innocence because he is not thinking about the fact that this is likely to get his wife in trouble. I think it is comical because he is asking a learned man (one who must have read lots of books) why reading books makes a person do strange things.