Accommodation refers to the way the lenses inside our eyes accommodate for the fact that objects of interest may be close to or at a distance. Sharp images on the retina are the result of modifying the focal length of each lens.
The focal length of a lens is the distance at which it brings parallel rays of light into focus on the retina.
A lens with a shorter focal length brings objects closer to the eye into focus and has a wider field of view.
A lens with a longer focal length brings objects at a greater distance from the eye into focus and has a narrower field of view.