Can someone help clear this up regarding R(^2) squared - covariance?

I'm analysing a regression analysis output, and i'm just a little confused on the R Squared output,

the formula for R^2 is r(X,Y) = [ Cov(X,Y) ] / [ StdDev(X) x StdDev(Y) ]

So breaking this down, is the Covariance the extreme values of both my data?

and

I know an Rsquared of 1.0 fits the regression line perfectly, mine is coming out as 0.456

so am i right in saying 40.6% of the time my investment performance is explained by risk exposure, and 59.4% is pure luck?

any help would be good thanks