There are many ways to learn UI and UI design like
.1. Through books
2. Online Course
3. Youtube videos
But I personally recommend learning under an instructor mainly from well knowledged and experienced trainers because they actually explain the concepts through real-time experiences they know what the industry needs and it is better to go for a certification course which helps to stand out from the crowd in interviews. If you want to learn through hands-on experience then I recommend you to go for UI UX Certification Course from Intellipaat.
Before enrolling in the course check out this tutorial video