MAN is an acronym for Mei Nukvin (female waters). A woman in Kabbalah is always associated with desire, a man with bestowal. A woman is a desire to receive, a man is a desire to give. Therefore, female waters means the rise of desire from the bottom up to the Creator. Moreover, they encourage the Creator to begin creation, correction, and fulfillment of these desires. In this case, requests from the bottom up are called prayer or MAN.
Question: Is that the MAN (manna) mentioned in the desert?
Answer: This is the MAN (manna), which the Torah says that every morning people picked up and fed on it.
Question: Very often in Kabbalah the term Machsom [barrier] is used. What does it mean?
Answer: Machsom is a state that a person must go through along the path from the sensation of only our world to the sensation of the upper world. In other words, this is the borderline between ours and the spiritual world, a kind of psychological barrier.
From KabTV’s “Fundamentals of Kabbalah,” 6/17/19