PV – is present value, basically what is the amount you currently owe or have invested.
r – is the interest rate, basically what percentage will they charge you per period. It’s usually written as a decimal number, so 5% is represented with 0.05.
n – is the number of periods (is it charged once per year – annually, or bi-annually – twice per year.)
FV – is the future value, what is the total amount you will owe or gain after all of the periods.