Looks like do not populate. All the components with value nB are in clusters around optional features.
Normally DNP would be just a note, but EasyEDA may not support this, so they had to put it into value, which is a horrible idea.
Ok I was thinking it was either that or a 0 ohm resistor.
One of the transistors in also nB, so it can't be 0 Ohm.
Noting from where it is in the schematic on pin 42 it could be an optional component. Like try it with and without it and see what the best results are.
If it were nb or Nb I'd guess it meant Nota bene, which usually means there's an explanation somewhere else. Is there any more documentation you could look through?
On my designs, I use DNP in my BOMs for do not place.
That's an German abbreviation: "nicht bestücken"
As others pointed out, it means "do not populate"