I’m going to assume that was a lot of words for “how can I learn to program?”, as the “I need to learn more about everything” hasn’t been a practical strategy since roughly the renaissance, if not earlier. And I’ll assume that this is not “I have an idea for an app”, as that too often runs afoul of the effort involved in getting from that idea to a product and a market. The idea is routinely a negligible part of the entire app development and product effort, there.
More generally, Apple is focused on Swift for app development.
Maybe start with the Swift language document (or eBook), and with a Swift Hello World program, or similar?
Also start with Playgrounds app and its Swift tutorials, and not Xcode: Swift Playgrounds - Apple Developer
Playgrounds are intentionally simpler than Xcode. Xcode is an integrated development environment (IDE), and is very capable. But Playgrounds are also very capable, and very useful. Why Playgrounds first? Learning both Swift and Xcode at the same time is a much larger effort, and learning Swift first will get you productive more quickly. (I use both Xcode and Playgrounds. Xcode is capable, effective, complex, and tends to change quickly. Those changes can unfortunately make tutorials quickly outdated, though. All of which isn’t all that helpful when starting out.)
As for learning more about the Swift language and syntax (in addition to the tutorials online), here is a (free) Apple book:
https://books.apple.com/us/book/the-swift-programming-language-swift-5-7/id881256329
If you’re just starting out with programming more generally:
Learn, Build, and Innovate - Apple Developer
Here are a Stanford iOS Swift course and an intro-to-programming Harvard Python course (both are college level courses, and free):
… https://cs193p.sites.stanford.edu/
… https://pll.harvard.edu/subject/python
For a wider introduction, and wider options, beyond Swift:
… I'm just starting out coding/programming - Apple Community
… Swift programming language for beginners – Apple Community
… Computer Science from the Bottom Up by Ian Wienand (free)