https://en.wikipedia.org/wiki/Enthalpy#Definintion
here must What does "work required to achieve its pressure and volume:" mean?
This is what I did make out of given answers : $$dQ=dU+PdV$$ for this work done by system is PdV
now meaning considering total work to form is = internal energy + work done to occupy the space which is $$nadT=d(PV)$$ therefore this total is going to be really: $$dH=dU+d(PV)$$ $$dH=dQ+dP**V$$ for opposite sign convention -dPV.