The hole in Jaime's chest is called a "Whole," and in short it's the idea of carrying God inside of you: a centre that feels everything from everyone by virtue of being connected as One.
I believe everyone has this God inside them to some degree because everyone has the capacity to love; but in order to truly make room for that Presence, one must give themselves away, and surrender their heart to the world. Jaime acquires this Whole over time when the connections she loves dearly have to be pulled out, taking pieces of her heart with them. When all's said and done, her heart is replaced with not an empty void of a hole, but a perfect Whole that emits a warm light.