Yes, the variable of interest is two-dimensional.
If you are making a graph about the area of a country, that is a two dimensional measurement. It would be ok to make a graph that is also 2 dimensional.
They are opposites. since |-3| has the lines around it, this represents absolute value, which is not positive or negative but how far away the value is from 0. the plain -3 remains the same. |-3| is 3, because it is 3 units away from 0 on the number line.