The first number is called systolic blood pressure because it indicates blood pressure during the heartbeat (systole), and the second number is called diastolic blood pressure because it indicates blood pressure while the heart is relaxed (diastole).
Angka pertama disebut tekanan darah sistolik karena angka ini mengindikasikan tekanan darah selama jantung berdetak (sistole), dan angka kedua disebut tekanan darah diastolik karena tekanan itu mengindikasikan tekanan darah selama jantung mengendur (diastole).