As much as it can be understood the author is either talking about two variables P and S or two vector variables.

In case of the first,

The interpretation is :

variables P and S are not independent. They are normally distributed with

E(P)=mu1

E(S)=mu2

Cov(P,S)= -rho.sigma1.sigma2

Var(P)=(sigma1)^2

Var(S)=(sigma2)^2