From LQWiki

ll (long list) will produce a list of a directory that looks like this:

-rw-rw-r--   1 user  user    9181 Jul 19 21:29 types_ref.txt
-rw-rw-r--   1 user  user   16698 Jul 19 20:29 vocab.txt
-rw-rw-r--   1 user  user     348 Jul 13 23:42 voc.txt

This command is typically an alias to ls -l.