A neshoma klollis is the soul of the leader of any particular generation or the yechida,some say the chaya-yechida. 

Let’s start with basics in Jewish soul-logy:

1. A soul is an extension from G-d (Tanya ch. 2) revealed (a little) in a body.

2. There are 600,000 general souls that split into 600,000 more souls and each gets a body.

There are five degrees of the soul:

1. Nefesh, gives life to the body. This is the “lowest” or most external expression of the soul and is able to be integrated in the body (ohr hanefesh).

2. Ruach, or spirit, also finds itself in the body.

3. Neshoma, from the word neshima, breath, also in the body.

4. Chaya, or alive, transcends the body. This degree of the soul can be found equally everywhere in the body, but is too great to be contained in the body. This is the center for will.

5. Yechida, means united. This is the pintelle Yid, the unbreakable essence of the Jew. This degree of the soul is the “closest” to G-d, one with G-d.

Back to neshoma klollis:

Imagine yourself in a house with many windows and the Sun’s rays are shining through those windows. In the metaphor the yechida or is the Sun. The Sun’s rays are the lesser degrees of soul and the windows are the bodies of the Jewish people.

The leader of the generation starting from Adam HaRishon, through the Avos, Moshe Rabbeinu, etc., the Ba’al Shem Tov, Maggid, Alter Rebbe, etc., Frierdiker Rebbe, our Rebbe is the yechida living in a body. That means that they have the most soul expression humanly possible, which means that they are the most G-dly people (not G-d chas v’sholom!!!) around. That’s why Moshe Rabbeinu is called “Ish HoElokim,” G-dly man, G-d man, or man of G-d.