If you’re interested in making sure your products look good and are appealing to users, then you should focus on learning UI design first. If you’re more interested in making sure your products are effective and easy to use, then you should focus on learning UX design first. But generally, UI UX is a combination. You have to learn both so you can gear up your future as a UI UX designer. If you are planning to learn this tool then I recommend you to choose UI UX certification course offered by Intellipaat which they provide you with all the required skills in UI/UX designing.
Before that, do watch this free tutorial video from Intellipaat if you're interested in learning more about it