Until it reaches “to the Land,” which refers to the level of Malchus, Malchus-Kingship is referred to as “the Land.” Just as the land is the foundation of all living things, and all resources come from it, so too Malchus is the direct force of Creation of all the created beings.
By bringing the lofty Wisdom into Malchus, it is then able to come into and effect all the created beings. This brings about Tikkun-fixing the world spiritually from its previous state of Tohu-chaos.
“Which I will show you,” which can also be interpreted to mean, “I will show and reveal you on your essential level.” That is, that you[r true essence] will become revealed through the mitzvah of Milah, as it says “And your name will be Avraham for the father of many nations I have made you.” (Bereishis 17:5)
On a revealed level, this verse means that through the mitzvah of Milah, Avraham will be famous as the “father of many nations,” meaning impacting all of the nations of the world. On a spiritual sense, this means that through the mitzvah of Milah, his true essential level of Lofty Wisdom of Holiness was able to descend into this world and effect himself and everyone he interacted with. This is the idea of “going to the Land,” i.e., bringing his level of Lofty Wisdom of Holiness “down to earth.”
As we see, that all the nations of the world know about Hashem because of the Jewish people who came from Avraham; and the other two “religions” that are practiced by the “descendants” of Avraham through Yishmael and Eisav have prepared the world for the knowledge of Hashem by introducing them to some of the concepts of the Torah (albeit taught incorrectly), as the Rambam writes in Hilchos Melachim chapter 11. (Even though Yishmael was born before the mitzvah of Milah, but he only had a bris after this mitzvah was given, which he continued to practice with his descendants etc.)
