What do the eight-character vitality and residual qi mean respectively?

The reason why the eight characters are divided into raw gas and residual gas is because the gas in the earth branch is mixed and dry for many days.

This qi means that there is a hidden stem in the earthly branch, which belongs to the five elements, so it is called this qi. Family, bank, same line.

Residual qi is the heavenly stem that contains other five elements besides the original qi in this branch, so it is called residual qi.