Q:

How the (-) operator converting negative numbers to positive works?

Here is an example:
def absolute(x):
    if x >= 0:
        return x
    else:
        return -x

print(absolute(3))
print(absolute(-119))

The Output: 
3
119

Now, how -119 became a positive number by just using the (-) subtraction operator?
Thanks.
Update:
For those who misunderstood my q,
So I'm repeat, How -119 turns to be 119 by using the (-) operator! as in return -x in the code above. Nope, I know it would be a multiplication but how it is achieved by using (-) operator?

A:

You seem to be confusing the binary operator x - y aka "x subtract y" with the unary operator -x aka "negate x". They are different things.
-x returns the negation of x. If x is positive, -x is negative, and vice versa.
Unary - is: https://docs.python.org/3/library/operator.html#operator.neg
Binary - is: https://docs.python.org/3/library/operator.html#operator.sub

