It means Intermittent fasting is good for lowering systolic blood pressure, but doesn’t do much for diastolic blood pressure. Systolic blood pressure is more strongly correlated to all sorts of health problems (both matter, but systolic matters more barring edge cases) so this is good

However, it’s basically saying that there isn’t some magical thing going on with intermittent fasting specifically, the only reason it’s good for lowering systolic blood pressure is because it’s good at helping you lose weight, but it’s no better at reducing systolic blood pressure than any other approach to weight loss