And what is a DBW?
The proper designation is ETC, for
Electronic
Throttle
Control. There have been many names given to this technology over the years (it isn't even remotely close to a new thing, been around for at least 20 years), such as fly by wire, drive by wire, etc. Those other designations aren't just limited to throttle control like the H-D system is; for instance drive by wire can include things like steering as well as throttle control, and fly by wire includes control surfaces as well as engine parameters.
In Harley's version, the throttle cables are eliminated. There is a sensor mounted in the end of the handlebar that is engaged by the internal teeth on the right handgrip. Turning the grip turns the sensor which alters the voltage signal to the ECM. The ECM uses that signal to determine how much throttle should be applied, and sends a separate signal to the throttle body actuator. That's the little electric motor that actually moves the throttle plate.
One of the advantages to this system is that H-D could eliminate the separate cruise control module and cable from the earlier versions. The cruise control now uses the ECM and throttle body actuator rather than a separate module/actuator/cable. Saves on parts, saves on space, saves them $$.
Jerry