CAR function returns the first element of list, that is the car part of its cons cell argument. CAR is identical to FIRST.

(car '(1 2 3)) => 1
(car (cons 'a 'b)) => A
(car (cons '(1 2 3) '(a b c))) => (1 2 3)
(car '()) => NIL
(car nil) => NIL