English term (edited): beam angle

"The disbursement angle of light projected from a Speedlight as it relates to lens focal length.\", which is the definition of \"Coverage\" in photography when using a camera flash

Speedlight is a make of camera flash, so the "coverage" in question is about what is "covered" [=illumined] by this camera flash, and that is defined by the "beam angle" of the produced light IOW this "disbursement angle" is in fact the "beam angle" of light produced by this camera flash.

This completely weird term appears ONLY in relation to LED light [the only ever mention of "disbursement" of light!] - sounds like some crap MT translation for "angle of distribution of light" form Chinese (the main manufacturers of LEDs) that is being uncritically repeated/propagated by translators who either haven't got a clue about the subject matter or just "obey orders" to stick to given terms.

IOW the ST rephrased correctly should sound like this:

"The beam angle of light projected from a Speedlight as it relates to lens focal length.\", which is the definition of "Coverage" in photography when using a camera flash

explanation: depending on lens's focal length, the field of view covered by the picture will be narrower (for longer focal distances) or wider (for shorter focal distances), so you have to use a camera flash with a corresponding/appropriate "beam angle" if you want your picture to be "covered" by its light.