Gibbs free energy ....
It's just a "plug and chug" problem. Plug in the numbers, turn the crank and out pops the answer. It's just arithmetic, once you get past Gibbs free energy it's barely chemistry.
ΔG° = -nFE° = -1(96,485 C/mol)(1.01J/C) = -97.4 kJ/mol
F is Faraday's constant and is the charge in coulombs of a mole of electrons. One electron has a charge of about 1.60x10^-19C.
The cell potential is in volts, but the volt is a derived unit. The MKS units for "volt" is "joule per coulomb".
The take-away is that a voltaic cell with a cell potential of 1V represents a "spontaneous" process (one that occurs on its own with no outside intervention). It's spontaneous because the sign of ΔG° is negative.
There are some other things to know about cells and Gibbs free energy. If the reaction is not spontaneous ΔG° is positive and the overall cell potential would be negative. Such a cell won't produce a voltage. Also, if the cell "runs down" (dead battery) and the potential is zero, then the system is at equilibrium. For a system at equilibrium ΔG° is equal to zero.