What is a Animation Event, and what are they for

[SanJoseYTXD (Spooky)]

when i was animating, i pressed an wrong button, and this of animation event appeared, what is it and how to use them?

[AridFights1 (Arid)]

What do you mean by an animation event, can you send a screenshot?

[SanJoseYTXD (Spooky)]

[AridFights1 (Arid)]

Here