X is one variable and y is another. The correlation is, given x, how likely can we predict y. So if x is IQ score, and y is income, and if there is a strong po

X is one variable and y is another. The correlation is, given x, how likely can we predict y. So if x is IQ score, and y is income, and if there is a strong positive correlation, then given high IQ (x) we can confidently predict high income (y). If there is no correlation between x and y, then given x, we cannot predict y.