Any Read nodes, the properties of which are open, will create a visual presence in the Dope Sheet. Here it looks a bit like a clip in a film edition, like Final Cut Pro or Premier. It can be moved forwards and backwards in time, and it's in and out points can be changed.
Additionally all keyed values show up in the Dope Sheet, but only if their properties panel are open. They may be made to permanently hang around in the Dope Sheet if the 'always appear in the dope sheet' parameter value is ticked in the Node tab, that is a feature of all properties panels. The amount of information the Dope Sheet contains is impressive, though a lot of this is neatly hidden behind its nested tree structure. In the screenshot below the Dope Sheet presents the key frames of a mere three points on a roto.
The main use of the Dope Sheet is to visualise any time-based edits that have been made and to make their place in time more easy to edit. As a key frame editor it offers pretty much the same functionality as the Curve Editor, but visualises the same information in a different way.