On a metal window awning that has folding wings.
The size is 48 in wide x 30 in projection. The window width
Is fine. But when you close the awning it is 54 Inches in length to cover the window entirely. So would it be 24 inches short in covering the window length wise. Is that what projection means?

Projection is the distance from the face of the window, measured parallel to the ground. That is a sun awning.