Answer:
It's a function that associates a real number x with a positive real number using the flowing definition: If the number is not negative (so either positive or 0) the absolute value is x. If x is negative, the absolute value is -x.
This means that to find the absolute value of x you must first determine if x is negative or not, and if it is, multiply it by -1. If it isn't, leave it as it is.
Since the absolute value is a function (of a given number), you can't just plot that number in the number line but the function (so in this case absolute value must be taken first.
The absolute value of x is never negative, so given the absolute value of x we can't determinate if x was positive or negative (if x =/ 0) before the absolute value was taken.