Sorry to be a Debby Downer, but having favorite design patterns is an anti-pattern. Favor the one(s) that works for the task you need to accomplish.

So I have learned coding by myself, I have good knowledge of HTML, PHP, CSS, JS etc and I have also done little bit work with Vue.js.

I think at the moment being Web dev is kind of my "dream job" (I'm 21, will finish my studies this year.)

Few people have recommended me few times to start using PHP Frameworks, so what really are PHP Frameworks, what are the benefits of using them, and which one should I start learning (Which are easiest to learn, which are most used at professional level?)

EDIT:

Thank you guys for all comments, I will read through them in peace and consider my next move.