Entropy can, at a simple level, be defined as a measure of the disorder of a system - ie it relates to the random, chaotic motion of molecules. The property of entropy comes in handy when describing the 2nd and 3rd laws of thermodynamics. In any case, all that is required here is a knowledge of the units of entropy. Basically entropy is represented by S in chem literature, heat as q, temperature as T. Then dS = dq(rev)/T. You can ignore the rev (reversible), and think of a change in entropy of a substance - ie change in disorder and chaotic motion of the molecules of the substance - as governed mainly by the change in heat (which is viewed as a chaotic energy change, as opposed to the more ordered work w). so, given that heat has units Joules/mole, and temperature has units Kelvin, entropy has units joules (or calories, but more conventionally joules)/Kelvin/mole.
