What does my contact lens prescription really mean?

I've always been told my vision is 20/20. Recently I went to get an eye exam so that I could get plano lenses to change my eye color a little, and the optometrist said I needed a mild prescription:

Sphere: -0.25
Cylinder: -0.75
Axis: 020

Sphere: -0.25
Cylinder: -0.25
Axis: 175

What do these measurements mean? And is it advisable to ask for plain lenses anyway? I've never worn a prescription before and I don't really see a point to wearing them if my vision seems fine.

Anything below 1.00 either +1 (for farsightedness) or -1 (for nearsightedness) can be attributed to stress in your life.ie… Studied a bit too much for exams under bad light conditions, lack of sleep, bad reading habits (posture etc.). But should fluctuate back to your 20/20 vision when the stress condition is removed. This is for the sphere reading.

Astigmatism (which is your cylinder and axis measurement) was taken because you wanted to get a fitting for your contact lens. That's why the optometrist mentioned you need lens… But those too are within and under the 1 variable. Its up to you if you want to get your contacts with prescription, but the lens with astigmatism usually cost more.

And if you are careful with your vision and rest your eyes I think you probably don't need them. But just in case get regular eye checkups.
Eat healthy, sleep do the things that keep your eye muscles happy (or drink a lot of carrot juice (good vit A for the eyes) etc and I think you would be fine. But I'm not a trained doctor, so if you want you should ask for a second opinion. But mostly I find that if your job/life doesn't require 20/20 vision (ie pilot) or 20/40 for driving (in the states) then you are safer not getting them, cause using glasses all the time or contacts can lead to worst eye strain and higher prescription, without solving what caused your eyes to strain in the first place.

Hope this helps, and keep your eyes healthy! You're lucky to have close to 20/20 vision!