"Pink is the new black" means: in the old days, black was the most popular colour, but now, pink is the most popular colour.
"30 is the new 20" means: in the old days, everyone seemed to be 20 years old, but now, everyone seems to be 30.
This blog is mainly to explain a different English language expression every day. Sometimes I post other stuff. I also have a YouTube channel which is mostly about computer software: https://www.youtube.com/englishspacedog
