Can you please deeply explain to me what Quaternion.fromToDirection does with an example

I am a beginner at coding and I’ve recently gotten myself some books to get started on coding and all has been going well until I can into contact with contact points and Quaternions(variable) and Quaternion.fromToRotate. I literally have no idea how this works, sources tell me that it rotates from fromDirection to toDirection but non of that makes sense to me.
Could you please explain in details as to what is for and please use an example

Also can you please enlighten me on how Physics.OverlapSphere work

Quaternion.FromToDirection changes a direction to a different direction see gif.

137675-quaternion-fromtorotation.gif

Physics.OverlapSphere will return all colliders found within or touching it. Picture a snowglobe, the house and snowman and other objects (with a collider) would be returned.