What is the role of reference electrode interface in PH meter

The PH meter is calculated using the electrode potential. So to measure PH, you have to put both electrodes in a solution and form a battery loop. Because the PH value is calculated using only a single electrode potential. The purpose of adding a reference electrode is to calculate the potential of a single electrode. Because the reaction of a single electrode is difficult, a reference electrode is usually denoting zero potential. In this way, the potential between two electrodes is the potential of a single electrode.