Aspect Ratio and Span Loading
As correctly stated above, aspect ratio is wing area divided by span. Stated another way, aspect ratio is wing span divided by the mean aerodynamic cord length. Gliders have very high aspect ratios as their wing spans are long and their cords are short. Fighter jets tend to have relatively low aspect ratios (short wing span and long cords).
Span loading is not a single, scalar parameter. Span loading refers to the distribution of lift along the span of the wing. In general, an eliptical distribution of lift along the span is close to the optimal with respect to maximizing L/D. Wing structural loads vary with span loading profile as well. The more the load is carried outboard, the higher the bending loads along the wing and particularly at the side of body where the wing joins the fuselage.
PPRUNE members with more of an aerodynamic background may choose to expand further on the general topic of optimal spanwise loading.