For change in entropy, units are

 Entropy change $\mathrm{\Delta S}=\frac{{\mathrm{q}}_{\mathrm{rev}}}{\mathrm{T}}$

$\therefore$ Unit of entropy is $\mathrm{J} {\mathrm{K}}^{-1}{ \mathrm{mol}}^{-1}$

The units of entropy are $\mathrm{J} {\mathrm{K}}^{-1}{ \mathrm{mol}}^{-1}$, which basically means joules of energy per unit heat (in Kelvin) per mol. Entropy is the measure of a system's thermal energy per unit temperature that is unavailable for doing useful work.

 J. ${\mathrm{mol}}^{-1}{\mathrm{ }\mathrm{K}}^{-1}$.