Shift letters for a 1992 chevy 2500. what does each mean?

P means Park. Put the shifter here every time you walk away from the vehicle. It is using the gearbox as a parking brake.It will roll a tiny amount as the park gear catches into position, but usually no more than the width of your foot. It doesn't matter if the engine is running or not.
R means Reverse. This is the position you use to make the vehicle go backwards.
N means Neutral. The Vehicle is NOT in gear so if left on a slope without the parking handbrake, (E brake), ON it will roll away.
D means Drive. This is the position you use for general everyday driving. It lets the engine use the whole of the gearing range.
S means Sport. This alters the setup in the gearbox to give the vehicle a slightly higher performance compared to the 'D' position.
B means Braking. More correctly called 'Engine Braking'. This is the gear you use if you are going down steep hills. Note some companies use 'L' instead of 'B'. It usually means Low, as in low gear.
It uses the gears in the transmission to create drag on the engine which acts as a braking effect. It helps prevent you 'riding' your brakes on really steep downhills. If brakes get too hot they don't work as efficiently.

Sounds like the reverse band or servo has gone out. Transmission shop needed for a confirmation.

can not reverse in the morning wen it is coll have to give speed for 30sce. and also for drive

Do you feel some play between the linkage parts?
If it's too much play, then that's the problem

Really?? Are you kidding? It stand for low, as in low gear (first or second on a manual). Low, Drive, Neutral, Reverse, Park....

no the fuse is for the 4 wd shift motor only, when was the transmission serviced last? if you don't know, i would start there

If you need further help, I’m available over the phone at https://www.6ya.com/expert/david_4c166ba81493f541

P = park
N = neutral
R = reverse
D = drive
1 = first gear only
L = low gear for towing and winter snow driving

c...

under the vehicle there is a shift rod with a nut on it loosen the nut and move selector on tranny to park then line lever in truck up with it and tighten nut.

Transmission range sensor may be failing. I would test it for opens and shorts.

theres a shift cable if its floor model,linkage for column model.