If calculating a correlation on two betas, then the units are already normalized: beta itself is the unit. However, if you want to correlate stocks, it's critical you normalize them into percent ...

A coefficient of determination of 0.347 indicates that Apple stock price movements are somewhat correlated with the index, as 1.0 represents a high correlation and 0.0 indicates no correlation.

Negative coefficients indicate opposite direction of movement in most cases. The other key result is the correlation of the two. Regression statistics will typically include an R-squared value.