The ‘digital’ is the easy part to understand. ‘Experience’ is every interaction a customer has with your company. How do they experience your brand? And ‘Management’ is how you monitor and keep track of everything so you know what messages to send and how to interact with your customers.
https://www.forbes.com/sites/danielnewman/2019/01/22/the-ins-and-outs-of-digital-experience-management/