This brief text contains two stories.  First Rebekah suffering pregnancy with twins, foretelling coming struggles between them.  Second, conflict between the brothers, foretelling the birth of the nation of Israel.  

At the outset, we would do well to recognize main character in these stories, Jacob, is later given the name Israel, his offspring are thus the Israelites.  The telling of the story is at the same time a telling of the character of a nation of people chosen by God.  Christians often forget that Jacob is Israel, and Israel is a person. The story, then, of Jacob becoming Israel, is a story of transition  of a culture from one state to another.

The foretelling of the coming struggle is the oracle of prophesy given to Rebekah suffering a  difficult pregnancy.  

And the LORD said to her, "Two nations are in your womb, and two peoples born of you shall be divided; the one shall be stronger than the other, the elder shall serve the younger.” 25:23

This prophesy is a kind of riddle which  seems to predict the subjection of the older and greater people to the younger and smaller people.  There is a common theme introduced here that repeats often in scripture, the unlikeliest chosen over the likeliest, as is the case with the next ancestor story of Joseph, and famously by the choosing of runty David over his burley elder brothers.  This same theme enters the New Testament with Jesus choosing rough-hewn fisherman and ministering to the last and the least.

But the prophesy remains a riddle, when the sons are born with Jacob gripping Esau’s heel. Who is born first?  The question is no small matter, given the law of primogeniture in the ancient world, the eldest son by law inheriting the family fortune, or at least (according to Babylonian Law) a double-share of the fortune.  Doesn’t Jacob have an equal claim? Is Esau entitled to primogeniture because he was born seconds before Jacob, though the entered the world as a one?

This conflict beginning introduces a story of further conflict, cultural, symbolic, and spiritual.

Esau is a hunter of animals, living outdoors, pursing game—a hunter gatherer.

Jacob lives a more pastoral life, indoors.  While he cannot be called an agrarian, he represents a more civilized lifestyle.  Esau, on the other hand, follows in the footsteps of Isaac and Abraham, representing an older lifestyle that was giving way to new forms of civilization.   

There is opposition and conflict as new forms of civilization arise (Jacob) and old forms disappear (Esau).  

The cultural and symbolic conflict between Esau and Jacob becomes a spiritual conflict between God and Jacob-Isreal as his story develops. This struggle begins with the bowl of lentil stew Jacob prepares for his famished brother (Does Jacob know from past hunts that Esau would storm in demanding to be fed?  Is this why he has food prepared with a proposition at the ready?)

Esau comes in hungry from a hunt, talking like a brutish sort, with crude vocabulary and thought only for the moment:

Let me eat some of that red stuff, for I am famished!” 25:30b

“That red stuff”?  

When Jacob sets the price as Esau’s birthright, Esau responds:  

"I am about to die; of what use is a birthright to me? 25:32b

Then, we see the strength, power, and shortcoming of Esau with five verbs in rapid succession: 

“He ate and drank, and rose and went his way.” 25:35b

The story concludes:

Thus Esau despised his birthright. 25:34e

The movement of the story shows Esau satisfying his hunger and thinking nothing at all about selling his birthright. Focus only present hunger, he squanders his future inheritance. 

Given the representative role this beginning story plays on the unfolding story of Jacob struggle in becoming Isreal, we might see in Jacob’s gripping his brother’s heel spiritual longing to be seen and recognized as equal and worthy of his father’s blessings.  By not passively accepting the lesser role assigned him, he represents both the transition from a dying cultural past to a new form of civilization, but also the spiritual struggle of coming to grips with who he is with God. This struggle is told and retold in scripture, with Jacob-Isreal showing us what it means to value our birthright in God.  

Resources
Genesis 12-36.  A Continental Commentary.  Claus Westerman.  Fortress Press Ed.: Minneapolis.  1995. 
The New Interpreter’s Bible. Vol. I.  Abingdon P.: 1994.