The longer answer
"Pull" is the word a shooter shouts when they're mounted, ready, and want the trap to throw. The convention is universal across English-speaking ranges, and you'll hear it called crisply — a sharp, single syllable that cuts through ambient noise. On many modern fields a voice-activated release is listening for the consonant shape rather than the specific word, which is why some shooters can get away with "mark," "go," or a grunt — though "pull" is what every puller and every machine is calibrated for.
The same word names the unit of trap throws. A scorer talks about how many pulls a squad has taken; a club books practice by the pull. In doubles, a single "pull" call releases two clays simultaneously — one call, two birds.