Product design course
uxdatabase.io
uxdatabase.io
Design, and UI design is a pretty hard thing to learn theory first. You gotta put it into practice by making something, thinking critically about it (and seek critique from others) and then remaking.
Just to throw another approachable resource in. https://www.refactoringui.com/
Open figma and start making something!
On the other hand, if you want a lighter introduction to design, try watching one of Gary Hustwit’s films like Helvetica, Objectified, or Rams. Or read the Design of Everyday Things by Don Norman.