I did a quick Google search. The following is an assumption.
Some platformer games have something called "coyote time", which means that the player still has the ability to jump after walking off a ledge for a few frames. So a coyote jump would mean maximizing your jump by jumping a little bit after walking off a ledge.
Coyote Jumps or Coyote Time is a term used to describe the time right after you walk off a ledge and it still allows you to jump or walk back.
That term originated from Wile E. Coyote from Looney Toons. In those Wile E. walks over the Cliff as if Gravity is not a thing for him. Animators called it mostly Coyote Time.
Some games have ledges that extend farther than what the visual ledge implies, so you can run past the ledge a little without falling. To us old people, it looks like a certain coyote from old cartoons. Basically, gravity doesn't apply to the coyote when he leaves the ledge, but later when he realizes it.
I have to keep reminding myself that these things aren't common knowledge. Then I feel old.
This is all correct information. Coyote time is a sneaky little feature developers use to make games feel a little less frustrating and/or make the player feel more skilled than they are. Most platformers abuse it in some way in speedruns. There is at least one platformer that notably does not use coyote time and is widely considered one of the hardest (at least among traditional platformers, precision platformers are another ballgame), and that's Crash Bandicoot.