Need to know the meaning of these two Statement

[Rajveer]

SET vSize = Div(Log10(fAbs($1)),3);

and 

SET vAmountFormat = Dual(Num($1/Pow(10,3*$(vSize($1))),'###0.00;(###0.00)')&Pick($(vSize($1)),'K','M','B'),$1);

[vincent_ardiet_]

Apparently you have a variable vSize which should be something like
RangeMax(RangeMin(1,Div(Log10($1),3)),3)
Or something else but which is returning a number between 1 and 3, 1 if the parameter ($1) is under 1 million, 2 if under 1 billion, 3 above.
Then the formula you are showing is dividing the number given in parameter by 1,000 or 1,000,000 or 1,000,000,00 based on what vSize is returning and adding 'K', 'M' or 'B' after this number.

[boazbo]

Let's assume that the first statement is true. In this case, the statement agrees with itself, so it is indeed true. Now, let's assume that the statement is false. In this case, the statement is incorrect, so it is indeed false. As such, the statement can be considered both true and false, depending on how you approach it.