No problem Kibou
What kinds of things do you want to learn about UI layout? Do you mean things like design principles such as the Gestalt, or actual design?
There can be a bit of confusion around terms with UX. In particular I think that mockups, wireframes, and prototypes can be confused together, and when you bring in fidelity that can also cause confusion.
Generally fidelity is the level of... "polish" I guess that your design has. So low fidelity are generally things like sketches, balsamiq mocks etc. Things that aren't pixel perfect and can't be considered the final design. High fidelity is generally when your design is finished or you need a high level of polish in order to present your idea. So it depends on your audience and what asset you are supposed to be giving them. For instance, if you are showing a storyboard and trying to sell an idea, you usually use high fidelity designs.
Wireframes: These are about functionality, such as navigation, spacing and prioritisation of content, and placement of different elements. They generally don't include any styling, colour or graphics.
Mockups: These are generally done after wireframes, they are more of a final result of what your product/solution will look like. These can blur into prototypes as some people do them in design programs, while others jump straight to html and css.
Prototypes: These can be low or high fidelity. These are generally used to test functionality, behaviour and interaction. They tend to be click through either images, or even html based.
So in terms of the process that I am used to, after you have completed your research, defined the problems you are trying to solve etc, you then move to ideation, where you come up with IA, journey maps etc. Generally after you have an idea of what you are trying to achieve and for whom, you can start sketching out ideas. After you narrow them down to several solutions you can then move to wireframing them.
I hope that helps.