From a certain PDF document:
"Here are descriptions of some of the main parts of the eye:
Cornea: The cornea is the clear outer part of the eye’s focusing
system located at the front of the eye.
Iris: The iris is the colored part of the eye that regulates the
amount of light entering the eye.
Lens: The lens is a clear part of the eye behind the iris that helps
to focus light, or an image, on the retina.
Macula: The macula is the small, sensitive area of the retina that
gives central vision. It is located in the center of the retina.
Optic nerve: The optic nerve is the largest sensory nerve of the
eye. It carries impulses for sight from the retina to the brain.
Pupil: The pupil is the opening at the center of the iris. The iris
adjusts the size of the pupil and controls the amount of light that
can enter the eye.
Retina: The retina is the light-sensitive tissue at the back of the
eye. The retina converts light into electrical impulses that are
sent to the brain through the optic nerve.
Vitreous gel: The vitreous gel is a transparent, colorless mass that
fills the rear two-thirds of the eyeball, between the lens and the
retina."
As for the question of why should take good care of our eyes. It's because our eyes serve as the one and only guide to visually sense the world around us. With our eyes, we could see colors and adapt more to certain changes in the environment. Plus, we could get to use our instinct to evade danger when the eyes detect them.
Hope this helps!