UX refers to "User Experience". UX design is the process of creating products that provide meaningful and relevant experiences to users.
At the most basic level, the user interface (UI) is the series of screens, pages, and visual elements - like buttons, call-to-actions or icons - that enable a person to interact with a product or service.
User experience (UX), on the other hand, is the internal experience that a person has as they interact with every aspect of a company’s products and services.
So UX design involves the design of the entire process of acquiring and integrating a product - including aspects of branding, design, usability, and function.