What does sic designate?

Answer 1

It's Latin for 'thus'. It is used when there is an error or an oddity in something you are quoting, to show that the person you are quoting made the mistake, not you.

Answer 2

"Sic" is used in written language to indicate that a word or phrase that appears mistaken is reproduced faithfully as originally written. It is usually placed in square brackets after the error to show that it is not a typo or mistake on the part of the transcriber.