What did Isaac mean when he told Esau that he had made Jacob Esau's overseer?
Isaac meant that Jacob was positionally placed above Esau as his lord or overseer. The word 'lord' there is a term of address, like 'dear sir' or 'my dear sir,' yet it designated Jacob's superior rank. Esau's brethren were also given to Jacob as servants, confirming Jacob's authority over Esau.
Les explains that when Isaac said he had made Jacob Esau's lord or overseer, the word 'Lord' in small letters is just a term of address—what we would call 'Dear sir' or 'My dear sir' today. It is a designation for addressing someone. So Isaac meant that positionally Jacob was above Esau; he was Esau's lord. Isaac added that all Jacob's brethren had been given to him as servants, and with corn and wine Isaac had sustained him. This came after Esau complained that Jacob had taken away his birthright and blessing, and Esau wept, but his status in faith did not change.