It's a fun and slightly old-fashioned way to say "everything" and emphasizes that you are referring to absolutely everything included.
Here are some examples:
* "I'm moving out, so you can have the whole kit and caboodle!"
* "He packed up the whole kit and caboodle and drove off to the mountains."
* "We're going to have a garage sale and sell the whole kit and caboodle."
It's often used humorously and can add a bit of charm to your speech.