Wizofoz
S is required as CL is only applicable to 1 section of airofoil. ie the wing is made up of many sections of airofoil so therefore S is required to find how much lift a wing with 'X' meters wingspan is producing.
I put it to u that CL is the same for a peice of airofoil with the same characteristics that is multiplied by S to determine how many peices of that particular airofoil is present.