LENGTH function computes length of the list, vector, string or other sequences. For lists, LENGTH may get stuck in cyclic cons structures unlike LIST-LENGTH.

(length "hola") => 4
(length "") => 0
(length #(2 'a 5.6)) => 3
(length #*101010101110) => 12
(length (list 'a 'b 'c)) => 3
(length nil) => 0
(length '(a . (b . nil))) => 2
(length (cons "moo" nil)) => 1
(length (cons "moo" (cons "boo" nil))) => 2