What is the difference between free energy and standard free energy
$\Delta G^0$ is change in free energy change in going reversibly from molar stoichiometric quantities of  pure reactants, each at temperature T and pressure 1 bar, to corresponding stoichiometric quantities of  pure products, each at temperature T and pressure 1 bar.  So $\Delta G^0$, $\Delta H^0$, and $\Delta S^0$ are all functions of T, but not pressure (which is fixed in the initial and final states as 1 bar).  The values of these function changes tabulated in your text book are all for 298 K.  But values at other temperatures can be obtained from integration, for example, in the case of $\Delta G^0(T)$ using the van't Hoff equation.
$\Delta G$ is change in free energy change in going reversibly from molar stoichiometric quantities of  pure reactants, each at temperature T and its own arbitrary pressure, to corresponding stoichiometric quantities of  pure products, each at temperature T and its own arbitrary pressure. If these arbitrary pressures happen to match the partial pressures of the same reactants and products in an equilibrium mixture, then $\Delta G$ will turn out equal to zero.  Otherwise, $$\Delta G=\Delta G^0+RT\ln(Q)=RT\ln{(Q/K)}$$and, for equilibrium, Q=K.