CASH is Hong Kong non-profit collection management company. They administer and enforce the rights of composers and authors of musical works subsisting under the copyright law of Hong Kong SAR. CASH at present controls the copyright of musical works of over 2 million local Members and Members from more than 80 overseas affiliated Societies.
Music Publishing is the business of protecting and promoting song copyrights and collecting the royalties that these copyrights generate. Think of a song as intellectual property (it's an original piece of art!), and music publishing as the business that makes sure that songwriters get paid a fair compensation when their intellectual property is used by companies. Those companies could be record labels (mechanical royalties), radio stations, bars, and restaurants (performance royalties), or film studios and advertising agencies (sync license fees), and many more.