What does Genesis 27:19 mean?

Old, blind, and near the end of his life, Isaac is planning to pass on the family blessing to the firstborn of his twin sons, Esau (Genesis 27:1–5). Isaac has sent Esau out to kill and prepare fresh game for him to eat before he bestows the gift. Rebekah, Isaac's wife and Esau's mother, has overheard this arrangement (Genesis 27:6–10). The two parents make no secret of their favoritism (Genesis 25:28). In fact, this imbalance was probably Isaac's motivation for attempting to bless Esau in private, as well as what motivated Rebekah to hatch her plot. Since she favors her younger son, Jacob, Rebekah pulls him into a conspiracy.

Now, with his mother's help—and insistence—Jacob is attempting to deceive his father, Isaac, by pretending to be his older twin brother, Esau. After being asked directly who he is (Genesis 27:18), Jacob now begins to lie in earnest. He says emphatically that he is Esau, adding that he is the firstborn, as if his father would not have known that. Jacob also rushes to close the deal, perhaps worried the Esau may return at any time. He asks Isaac to quickly eat the meal and bless him.

More specifically, Jacob says he is ready for Isaac's soul to bless him. The passing on of the family blessing will be an act of Isaac's will, a gift from his soul to his son and the generations who will follow.