For an ellipse equation in standard form, the length of the major axis is 2a, length of minor is 2b, for
(x-h)2/a2 + (y-k)2/b2 = 1. (h,k) is the center of the ellipse, which in this case is just (0,0). Note that the a2 and b2 can change positions in this equation. a is just the bigger of those 2 parameters.
Turning to the specific question, we need to divide both sides of the equation by 32, so we have it = 1:
x2/8 + y2/4 = 1. So a = 2√2 , and b = 2. The ellipse is oriented horizontally (its major axis along the x-axis), with a major axis length = 4√2 and a minor axis length = 4.