What are these guides and how do I turn them off?

I was in the middle of tracing this low res graphic with the bezier and shape tool and these dimension guides began appearing (jpeg attached.) I apparently inadvertently turned a feature on and would like to turn it off because I find the guides distracting. I opened the "dynamic guides" menu and deselected everything but that was not it. I've never seen these before. What are they called and what is the purpose of them?