@jenna16bella
My best guess is your talking about your heart rate according to the numbers you cite. It sometimes is written written 120/80/72 or 120/80/72/18
120 systolic pressure,
heart is beating ( max force)
80 diastolic pressure
at rest (min force)
72 heart rate (pulse)
18 breaths per minute
You may be talking about pulse pressure which is the difference between your systolic and diastolic pressure (120-80=40.) Normal pulse pressure is 30 to 50mmHg. Although not often written this way it is possible to see 5 numbers
Diastolic pressure
Systolic pressure
Pulse pressure
Heart rate
Respiration
Hope this helps answer your question.
Jake