Is 120/90 a good blood pressure level for a 48 year old man? what does the 9 represent? thank you.

Diastolic HTN: 120 is excellent. But the 90 needs to be worked on. It indicates that your diastolic blood pressure is high which means your heart is working against more pressure than it would like to. Minimize salt, try dash diet, exercise, lose weight, don't smoke, and avoid stress and you may be able to get it to around 80 millimeters of mercury where it should be. Good luck to you.