Isaiah spoke of the future redemption of the house of Israel from those who would oppress them. The imagery is one where there is a reversal of fortunes, and Israel would eventually ascend over those who had oppressed them.
When Nephi asks Jacob to preach on theses, the phrase that the “kings shall be thy nursing fathers, and their queens thy nursing mothers” would be applied to the present Nephite audience (see 2 Nephi 6).
In this exegesis, Nephi will be linking this event to what he saw in his prophetic vision associated with the Tree of Life. Interestingly, it will be right after Nephi explains that the scriptures can have both temporal and spiritual meaning. That will allow Nephi to use these verses in different contexts with different interpretations depending upon the point he is making at the time.
In the previous verse, Isaiah said that the gentiles “shall bring thy sons in their arms, and thy daughters shall be carried upon their shoulders.” These descendants that the gentiles will bring will become the nursing fathers and mothers of the people. In Nephi’s likening, this was literal. The presence of gentiles in the New World who united with the Nephites would literally bring them sons and daughters. They would literally, as well as symbolically, be the nursemaids to the young Nephite nation.
As a result of the efforts of these saving gentiles, the nation would prosper and Jehovah would contend for them against their enemies. In Nephi’s likening, these gentiles would help to fulfill the promise of the land, that they would both prosper and be preserved upon faithfulness to Jehovah.