Teenagers today use slang words such as "bae," whose letters stand for "before anyone else" and which refers to a significant other, and "on fleek," which means something is on point or very good. "Basic" is used to denote something very mainstream and not cool.
Slang is non-standard words in a given language that are constantly changing, and teenagers love to use the newest words to express themselves. Sometimes teens even make up their own words amongst their social group. The Huffington Post points out how quickly these words change popularity from one year to the next. Some other newer terms are phrases like "turned up," which references the song "Turn Down For What" by Lil Jon and means to get pumped up and excited, and "lit," which describes something that is super cool and fun.
According to the San Jose Mercury News, many businesses stay up to speed with what slang teenagers are using so that they can market to them in their own spoken language. In weekly updates, companies discover and define new slang terms such as "throwing shade," which means to disrespect or publicly denounce someone, and "Dat ____, doe," which means that thing is awesome and very much appreciated.