It is a numerology term.
Usually used to explain the balance of the five elements in a person's birth horoscope. In this case, "birth" refers to the combination of heavenly stems and earthly branches in the year of birth, "lack of earth" refers to the lack of earth element in the five elements, "horse" refers to the earthly branch with horse in the natal life, and "pantu heavy" refers to the earth element in the horoscope. There are more occurrences.
It should be noted that these terms are just a symbol and form of numerology. You should not believe and rely too much on them, and you should look at your own destiny and life rationally.