As a front-end developer, you need to focus on how your application looks and how it feels to use it. A big part of that is designed, before building a website you should prototype how you want it to look, design how your users will interact with your application, how will that fit with the use case of your application, and what you want to accomplish with it, how to make it so that your users like using it and more. UI/UX is a specialization of its own, but every single front-end developer should have strong foundations in UI/UX regardless. Most big teams will have designers which will prototype applications using tools like Figma, Framer Motion, and various other tools. As a front-end developer, your task is to turn those designs into functioning code and hook all of the components to the APIs and databases necessary as well as creating the functionality of the application.
One of the most popular tools to prototype and design websites is Figma, so every FE developer should know how to use the application.