What do you think it means when the change is positive? Negative? in a mathematical way

This is the rules:
Rule 3: Subtracting a negative number from a negative number – a minus sign followed by a negative sign, turns the two signs into a plus sign. So, instead of subtracting a negative, you are adding a positive. Basically, - (-4) becomes +4, and then you add the numbers. ... This would read “negative two minus negative 4.”

Person above has defined it