Granularity here refers to the unit of the information.

Being more granular means it's more clear, like a sentence, a title, a concept.

Being less granular means it's less clear, like an article, a podcast, a video.

It is very difficult to master the technique of being able to extract more granular information from a less granular source.

This may be the least granular information.

More notes does not mean more information.

Usually we only take a small amount of notes because the notes only encodes new information that we do not know.