This is the pAg of the emulsion when made, and has no relationship to pH or to developed silver. It is for bromide emulsions.
The only similarity between pAg and pH is this:
pH = negative log of the hydrogen ion concentration. The lower the number, the higher the amount of hydrogen ion and the more acidic.
pAg = negative log of the silver ion concentration. The lower the number, the higher the amount of silver ion in solution. This measure is no longer used at Kodak. We use a vAg scale which is the actual measured voltage.