I had an eye exam yesterday and my notes say i have degenerative mytopia. my prescription is -6.00. what does that mean? is my vision terrible?

An exaggeration?: Degenerative myopia is well described in those with very high myopia (over -15). You have -6.00 and degeneration of the eye related to that degree would be quite unusual. Whoever told you this obviously has upset you; I would suggest a second opinion to set you at ease as I doubt that you have degeneration. If you are corrected to 20/20, you do not have terrible vision.