This is the 13934th most frequent Spanish word.
soplar
To blow.
In this case, 'soplar' represents the action of forcing air out of the lungs, as when blowing into something.
Antes de inflar el globo, necesitas soplar aire en él.
Before inflating the balloon, you need to blow air into it.
This usage of 'soplar' refers to the action of the wind blowing, a natural phenomenon.
El viento comenzó a soplar con fuerza esta mañana.
The wind started to blow strongly this morning.
Here, 'soplar' is used in a colloquial context meaning to secretly give information, typically by whispering or communicating discreetly.