Why is JAX-WS described as one of the frontends for Apache CXF? http://cxf.apache.org/docs/frontends.html
I only understand JAX-WS to be an Java api for creating web services.
In this case, frontend is not a GUI frontend rather the frontend that exposes JAVA APIs as a web service (hence, frontend). As described in the link you mentioned, there are different "frontend"(s) or rather modes of exposing and/or consuming the webservices you develop. JAX-WS is for SOAP, JAX-RS for REST and JavaScript services/client.