This is the 13292nd most frequent Spanish word.
pulsó
"Pulso" is the third-person singular simple past tense of "pulsar," meaning "he/she/it pressed or tapped."
Here, 'pulsó' refers to the action of pressing a button or a key.
Él pulsó el botón para encender la máquina.
He pressed the button to turn on the machine.
In this context, 'pulsó' describes the action of pressing a piano key to produce sound.
Ella pulsó una tecla en el piano para comenzar la melodía.
She pressed a key on the piano to start the melody.
'Pulsó' is used here for activating a stopwatch by pressing its button.