Question

What information is gleaned if we reject the null hypothesis for the test of the slope of the least squres regression line?

Answer 1

The slope is nothing but the regression coefficient. The conclusion is that the concerned variable characteristics are not linearly related or the regression line is not of "best fit"

Explanation:

I have modified the question as follows:
What do we conclude when the null hypothesis regarding the slope of the regression equation is rejected:
Rejecting the null hypothesis implies the regression line is not a good fit.