Sorry, I was using the wrong word, I mean the animation notify:
You define these on the animation and can bind these to events in your animation blueprint, and from there you can access them or call into your owner character to update it if needed.
Note that it matches up based on the skeleton used in the animation blueprint, and the skeleton targeted by the animation, so if those don’t match, your animation blueprint may not see them as possible notifies.
There are some samples in the unreal starter content that do this for Jump, for example, to always jump when the foot lands.