ENGINE refers to the engine assembly. The engine assembly is dictated primarily by which transmission was specified for that car and whether or not the car had A/C. This can be reversed engineered by asking yourself what engine (i.e Hemi or 440) what transmission (099) = four speed behind a Hemi or 440, and what body (at this point, I'll presume it's a B body). Since it's a Hemi/440 four speed we know it doesn't have A/C.
TRANS indicates the transmission assembly. 099 is the late number for the 68 Hemi/440 four speed.
AXLE = axle assembly number. This indicates the gear ratio, width, Sure Grip or not and brake size of the entire assembly. For 1968, axle assembly 246 = B body, 9.75 Dana, 3.54 gears with SG and 10" brakes. confirms it's a B body.
STEERING COLUMN = assembly code and color for the steering column. This assembly number would include info on whether the car was built with column auto, console auto, column manual or floor manual. Since it's a four speed car, we can surmise this is a B body steering column for a floor mounted transmission. the "X" tells us the column is painted black.
STEERING WHEEL/HORN RING Tells us which horn ring came on the car and the color of the wheel.
STUB FRAME = the K frame assembly number.
I'm guessing this 68 Charger with 440 four speed Dana combo; woodgrain steering wheel and front disc brakes.