Two Variables covariance matrix

Hello this is my first to your nice community :)

I know that a variable X that is assumed to follow the gaussian distribution is denoted like this

X~(median,variance).

I have found today the following

Yfrog Image : yfrog.com/b9correlationcoefficientsg

probably the author of the equation above is talking about two variables P and S. I do not know how to

a) read the equation above and

b) how to convert the variance correlation matrix to variance values for each of the two variables.

I would like to thank you in advance for your help

Best Regards

Alex