If the zeros = -3, 0, and 2, then x = -3 and x = 0 and x= 2 are input values for x giving real zeros for the polynomial. Degrees: 3 means the largest sum of exponents in any term in the polynomial is 3, like x3.
So when x = -3, x+3 is a factor of the polynomial. If you do the same for each real zero, you get (x+3)(x)(x-2). Now multiply the first two terms together, then then last two. Remember to use the FOIL method at the end. Let me know if you get stuck.