SPH, for Spherical, refers to the refractive correction in the prescription. Minus (-) are for near sightedness, and Plus (+) values are for far sightedness. If "PL" or "Plano" is written for the either SPH value on your prescription, you should select a value of 0.00.
OD-SPH is spherical correction for your RIGHT eye.
OS-SPH is spherical correction for your LEFT eye.