How do you progress from coding console apps to developing fullstack applications?

Hello, I am enterring my third year of taking my bachelors degree of software engineering and I am geniunely confused of fullstack apps. I was assigned to make a fullstack app by learning from online resources and I followed a video on how to make one but still to this date I don't understand a thing about it. I mean, I have made and will make countless codes that can run on console and forms like in visual studio. But I've never really understood how peo