Zeraph

My question is about the first variable in the seven variable equation (N = R x fp x ne x fl x fi x fc x L). Some list it as R or the rate of star formation in our galaxy, and some list it as the amount of appropriate stars in our galaxy. Can it be either?

If R is the rate, then would that make the final result, N, the amount of civilizations we can talk to that are born each year? Or the total amount available in our galaxy?

Thanks.