In my own words, South Africa Standard English are words that are borrowed from indigenous South African languages and are blended with English words for example braai for barbecue from Afrikaans
Jargon refers to words used by individuals from a particular profession, occupation or group of people. For instance, doctors, lawyers, and engineers often use particular terms to communicate with each other.
Slang are informal words used by groups of people to communicate orally, through texts, or in writing. Common slangs are bromance, frenemy, woke, and salty among others.