Janitor is a compound sign. First, sign clean, then sign person. To sign 'clean', lay your flat, non-dominant hand in front of you with your palm up, and wipe across that hand with your flat, dominant hand. Then, sign 'person' by having both flat hands face each other in front of your body, then pull them down simultaneously.
Teach your toddler the janitor sign when you are seeing such a person cleaning your or your spouse's office when you drop by for a visit, or when you see a janitor in a cartoon or your kid's storybook.
Teach your toddler this sign in conjunction with other job flash cards. It is good for your toddler to be acquainted with the different kinds of people who do essential work that benefits the entire community, like keeping the surroundings clean.