For this case the term "how much" is used to know the quantity of a variable that can not be counted.
For example, to know how much an object weighs, to know how much liters a tank has, we use "how much"
This is different from using "how many".
"How many" we use it to ask about numbers that can be counted
For example, to know how many people are in a place.
Answer:
It is used to ask questions regarding quantity.