。
My eyes are really sensitive to light.
Literal
Eye [subject-が] light [to-に-対して] very sensitive is-(explanatory-のです).
~に対して ('with respect to / toward') is the complex particle used to mark what something is directed at — here, what the eyes are sensitive *to*. のです at the end is the explanatory/causal frame, softening the statement into 'the thing is, my eyes are sensitive' — often used when offering an explanation or context rather than a bare assertion.