UI (User Interface) and UX (User Experience) developers are software developers who design and build user-facing interfaces. In general, developer manipulates user behavior to provide meaningful and relevant experiences to users. This involves the design of the entire process of acquiring and integrating the product, including aspects of branding, design, usability, and function. If you want to become a UI/UX developer then I recommend you to go for UI UX design course from Intellipaat which help you to become a professional developer.
For your reference, I am attaching Intellipaat’s UI/UX complete course video