What this means is that it's in your power to repent (just like the Ninevites!) and God will forgive you. It's an affirmation of free will and a repudiation of the doctrine that you need someone else to die for your sins.
Adamic sin is shared by all humans and only the perfect sacrifice of Jesus Chrsit was sufficient to cleanse us and to restore us to the Father. He freely offered himself for all of us collectively but it is up to each of us individually to come to the Father thru Jesus Christ. I think one finds the heart of what the Melchizidek priesthood is all about in Ezekiel 18, of which Jesus Christ was Chief Priest! One may repent but the sin stain could not be wiped merely by the blood of animals...but even in OT times, God imputed righteousness and even a knowledge and certain presence of himself to those, who in spirit and in truth, sought to live in God’s way! As Habbakuk says...”The just shall by his faith”!(and not by works alone lest any should boast as per Paul the apostle)