You may study English for years and still not understand a native speaker(说本族语的人) of English when you meet one. Many language learners know that native speakers say a lot of things that you can't find in a dictionary. Well, here's a secret for you: A lot of British people can't understand each other either!
Across the UK, a number of areas have different dialects (方言). There are many different accents (口音) in London, because it is not just where a person is born in the UK that decides their accent. Language and accents also change across social class and level of education. People from different countries and different age groups add to the influence, too. And so, "Multicultural London English" was created at the end of the 20th century.
"Yoof culture" is an example. The word "yoof" is a slang (俚语) spelling of "youth". Young people are creating their own language by using words that their parents don't understand, children can talk about things that their parents might not agree with. For example, instead of saying something like "That's good!" or "I understand", yoof will use a single word like "Safe!", or "Sorted!" Yoof would use "kind-a-thing" or "sort-a-thing" to replace "if you understand what I'm saying". In this way, they are starting to find freedom, independence and self-expression.
As learners of English, we may wonder how well we can talk to a native speaker, but perhaps we should worry less about this. Research by the British Council shows that 94 percent of the English spoken in the world today is spoken between non-native speakers of the language. In fact, when we think about "International English", there is no such thing as a native or non-native speaker. The UK no longer owns the English language.