As people learn English, either as a native speaker or a someone who is learning it as an additional language, no build the core English skills you need before you learn to speak English in a specialized. For native English speakers this is usually done through post-secondary education as part of getting a degree or certificate and then on the job training. For EFL students, this is done by first completing EFL training that gets them to an intermediate or advanced level. They then enroll in specialized English programs such as Business, Law, or Medical English. Through either path your General English foundation is built upon by adding specialized vocabularly and concepts, as well as ways of using that language in preparing specialize document, running specialized discussions (patient interviews), and specialized presentation skills (speaking at conferences).
What is General English?
to be contiued.