does anybody know what is this for the little blue piece and the another one next to it? it's a G20 1981.

 

These are vacuum fittings. I'm guessing these two are part of your emissions control system. You should be able to google and find a vacuum diagram for your specific engine/year/vehicle. Clearly someone has disconnected stuff which is not uncommon in older vehicles. If you don't have any drivability issues just leave as is.

 

May want to cap them off so there's no leaks or issues. That hose isn't looking too healthy either.