Need help in understanding the formula in the last three lines:

Consider again a general game with population uncertainty (T. Q, C. U), as in Section 2. In a play of this game. let X(c) denote the number of players who choose action c, for each c in C. Let X = (X(c))cec denote the action profile of all these numbers. These numbers X(c) are random variables whose probability distribution depends on the given type distribution Q and on the strategy function o that predicts players' behavior as a function of their types. To be specific. for any vector x in Z(C), the probability that X equals x is P(X=x: 0) = [ Q(W) II w(t)! II o(c . t ) "(c.1) W =F(x) t . - T CC w (c,t)! where F(x) = {WEZ(CXT) | EteT W(c.t) = x(c). VceC}. w(t) = [ w(c,t). and w = (W(1)), T