Find all files (type f) in the current directory (.) and its subdirectories (maxdepth 2) with any name (*.*) and execute the command (exec) to remove all characters except A-Z and newline (tr -cd 'A-Z\n'), sort the output, count the number of occurrences of each line (uniq -c) and print the fourth field (cut -f 4 -d" ") of the output.
find . -maxdepth 2 -type f -name "*.*" -exec tr -cd 'A-Z\n' "\\\\0" \; | sort | uniq -c | cut -f 4 -d" "