The cell reaction of the galvanic cell, Cu(s) / Cu2+(aq) // Hg2+(aq) / Hg(l) is
General cell representation is
Anode // cathode
Negative electrode // Positive electrode
Oxidation half cell //Reduction half cell
Double vertical line represents salt bridge .
At anode Metal looses electrons and undergoes oxidation and at cathode meal ion undergoes reduction.