Final answer:
The correct action that indicates an understanding of hand hygiene is rubbing hands together for at least 20 seconds.
Step-by-step explanation:
The correct action that indicates an understanding of hand hygiene is rubbing hands together for at least 20 seconds. This step ensures thorough cleaning of the hands and helps to remove microorganisms effectively. Hand lotion should not be used before washing hands, as it can create a barrier between the soap and the skin. Rinsing hands quickly under running water is not sufficient to remove microorganisms, and skipping hand hygiene if gloves are worn is incorrect because gloves can still have microorganisms on their surface.