Your Rx is what an ophthalmologist (an MD) or optometrist (a doctor of optometry) provides to correct your vision with a pair of eyeglasses with corrective lenses.
(You need an Rx written specifically for eyeglasses; an Rx for contact lenses will not work for eyeglasses!)
An Rx will have horizontal rows or vertical columns. The top row or first column will always be for the right eye, abbreviated as OD. The second row or column will always be for the left eye, abbreviated as OS.
Each row of an Rx has three main sections: Sphere (SPH), Cylinder (CYL), and AXIS. The SPH section corrects nearsighted or farsighted vision. The CYL and AXIS sections correct an astigmatism.
There may also be a fourth section on the Rx , NV-ADD (for Near Vision-Reading ADDition), which could be used to order a pair of bifocal or progressive glasses with a close-up vision section in the bottom part of the lens.
The SPH, CYL, and NV-ADD numbers will always have a plus or minus sign.