Trying to find out what this is called and how to make one?

[Charles29862383q73b]

[Jumpenjax]

These are printer notes and I am sure they are created through Acrobat.

[leo.r]

If I understand your question correctly then this plug-in (no affiliation) could be what you need:

https://www.tripletriangle.com/#functionality

It's not exactly cheap - but if it works as advertised on their website then it's quite powerful.

This thing in your screenshot is often called "slug" btw.

[Eugene Tyson]

They are called infotables or legends - plenty of names for them.

You can generate them manually - or through XML - or through a script 

There's plenty of ways to generate them.

Most information could be prepopulated if supplied.

If not supplied, then manual entry is required. 

They are usally placed in the slug area (which you can do in the document setup and go to Bleed & Slug area) it doesn't usually matter if it's top, bottom, left or right.