The P value

P value = 0.0005
a value = 0.05

Therefore we reject the null the hypothesis and accept the alternative hypothesis because p value = 0.0005 is smaller than the alpha value.

Test the significance of R square value
R square value = 0.835 (very strong relationship)
N=40

There is a positive, very strong and significant association that a person's BMI is related to his weight. (R=0.835, P=0.005, (P<0.05), n ="40