What would be the physical interpretation of the equation dG = Vdp − SdT?
For a continuous flow system operating at steady state in contact with a constant temperature reservoir at the same temperature as that of the entering fluid, and with negligible change in kinetic energy and gravitational potential energy, the reversible shaft work per mole that the system does on the surrounding is equal to the integral of -vdP, where v is the fluid molar volume.  So $\Delta G$ per mole is equal to minus the shaft work per mole.