org-mode is an extension for emacs. It's centered around a plaintext markup-format which is specialized for organization and note-taking, hence the name. It has several other extensions build up on the core-extension, and it's format, many coming from the original project itself. And it has later branched out into other areas, like literate programming, personal databases, etc.

Seems org-review is one such extension.

And a sketchnote is a visual note, something where you draw/sketch your information. Basically a more freestyle diagram or something to tell a short story.