What does this mean in terms of eyesight - CYL -R--2.25, L - -2.75

Cyl is the cylinder. If its minus it means you are nearsighted, if its plus you are farsighted.

R or OD means right eye, L or OS means left.

-2.25 is your prescription for your right eye.
-2.75 is your prescription for your left eye.

ChihuahuaMomma is right. A bit of extra info - the unit of the numbers is diopters (eg -2.25 diopters) Though not mentioned it is universally applicable.
Also since you have Cylindical correction, the prescription should also mention the axis which is not mentioned on yours.