The correlation coefficient is the measure of correlation between two variables, it basically determines wheter the variables have some type of correlation or not. The value can go from -1 to 1, where values between -1 and 0 represent a negative correlation, the value 0 represents no correlation at all, and values between 0 and 1 represent a positive correlation. This values can helps us interpreting a scatter plot by providing a estimate of the correlation between the variables.