What does "content-only" project mean?

I’ve seen references to “content-only” projects in the tutorials and documentation I’ve been reading, but I don’t know what that means. Could someone clue me in?

Most recently I’ve seen it in the description for Rama’s Blueprint Nodes

I’d also like to know what exactly people mean when they talk about a “content-only” project… any one able to answer on this yet?

“content-only” is when you have no c++ class in your project.