Middle Knowledge (Molinism)
This verse, along with the section in 1 Samuel 23, demonstrate that God knows more than simply all true prepositional knowledge. He also knows how all people would freely choose to act in any given scenario. Understanding this concept is instrumental to reconciling how God can be utterly sovereign in His plans and in dealing with mankind, yet give men free will and the ability to choose. Without middle knowledge (or "Molinism"), one is forced to abandon (or at least heavily diminish) one's concept of sovereignty, or one's concept of free will.
Jeremiah 23:22English Standard Version
But if they had stood in my council,
then they would have proclaimed my words to my people,
and they would have turned them from their evil way,
and from the evil of their deeds.