Rashi on Genesis
הן WELL! — an expression denoting agreement with a statement.
Sforno on Genesis
לו יהי כדברך, so that you will be satisfied with the results of your own proposal. [Lavan assumed that Yaakov had shot himself in the leg with his proposal. Ed.]
Siftei Chakhamim
A term indicating acceptance of terms. [Rashi is explaining that here it is] not like הן לי לא נתת זרע (15:3), which means הנה (behold).