The Daily Mail is using the headline "Tongue-tied Millennials Use Apps Rather Than Talking", for a story that almost half of young people today prefer to use social media and apps to talk to people they don't know, rather than face to face.  The research carried out by Cancer Research found that whilst two-thirds of over 55s are happy to speak to someone they don't know in person, 18 to 24-year-olds avoid proper conversations.  (I think most young people do that, all that has changed is that they can now hide behind their online persona.)

In English, if you are "tongue-tied", you are too shy or embarrassed to speak, and the term "millennial" is often used to describe someone reaching young adulthood in the early 21st century.