What is the 24 hour rule for KLM?

https://central.xero.com/s/question/0D58V00009CWE2TSAX/klmcustomerservice-what-is-the-24-hour-rule-for-klm-callf

KLM’s 24-hour rule offers flexibility for passengers, allowing them to make changes to their bookings or cancel their flights within 24 hours of purchase without any penalties or fees. To take advantage of this policy, customers can contact KLM’s customer service by phone. Klm customer service contact phone number.