What the team does | tr -cs 'a-zA-Z' '[\n*]' | grep -v "^$" | tr '[:upper:]' '[:lower:]'|?

Question

linux

Sorry for the dumb question, but what does the command above do?
I understand that capital letters are replaced with lowercase letters, uppercase words are replaced with lowercase ones.

Answer 1

replaces all English letters with a newline
searches for all non-empty lines
converts uppercase to lowercase (as I understand it is no longer English)