Camera frame

I just started with Unity. I’m working with tutorials, currently 2D. In this videos is always a border around the camera, which displays the field of view. Unfortunately, this is not visible to me and my question could not answer the tutorial authors. I hope here I can get help.

Maybe that a menu in the upper left corner of the game view is set to “Free Aspect”? If I change this to somewhat for example “4:3” I get the border too.

hello, thank you for you response.
But unfortunately it is not what i was looking for. i will attach an picture of what i think off.


maybe this will help to find the solution

I am sorry, don´t know.