Question Whats an euler angle?

So I've bean trying to learn bolt and watched some videos on making fps cameras and I've seen many people use euler angle. Sorry I'm not the best with math angles so this might seam dumb but what exactly is an euler angle? Is it like the direction an object is pointing? I'm really sorry if this is in the wrong section of the forums
( I'm new to the forums so bare with me ) but being I've only seen it used in visual scripting this was the only place I thought to go to.

 

I would suggest reading this page about rotations.
https://docs.unity3d.com/Manual/QuaternionAndEulerRotationsInUnity.html

Rotations are a tough subject first, but become easier the more you work in 3D.