People always ask me to give them my resources and recommendations to begin with Unity,
so here is my personnal Unity Ultimate Resources Guide ™

Documentation :

Everything start with a documentation

• Unity Manual : the official documentation of Unity, very well written and exhaustive
• Script Reference : the scripting documention for developers
• Universal Render Pipeline Docs : the documention of the URP, which is the default renderer to go with
• High Definition Render Pipeline Docs : the documention of the HDRP, the advanced renderer for photorealistic games

Troubleshouting :

When the doc doesn't have the answer...

• Unity Forum : Unity has the biggest game dev community, it's really helpfull
• Unity Answers : Stack Overflow but for Unity, if you have any problem it's probably solved here

Tutorials

The best places to learn

• Code Monkey : The best tutorial youtube channel for Unity, I highly recommend to follow the Intermediate/Beginner Course
• Unity Learn : The official Unity tutorials, a lot are outdated but there is some good ones
• Unity Youtube Channel : It contains some tutorial, as well as the official annoncements
• Brackeys : The channel was stop few years ago, but it was a really great channel for beginners
• Tarodev : It features a lot tips, small tutorials and really good best practices
• InfallibleCode : A lot of code best practices and design paterns tutorial in here
• Freya Holmer : Math for gamedev made "easy" to understand, I also recommend to follow her on Twitter
• Catlike Coding : Techart tutorials for Unity

Miscellaneous

A list of random stuff, you can find useful

• Ryan Hipple : Game Architecture with Scriptable Objects : A talk about a super powerful dependancy injection pattern using scriptable objects, I highly recommend to use it
• Scriptable Object Architecture Implementation :  A full blown implementation of the Scriptable Object Architecture by Daniel Everland
• Unity Script Collection : A github regrouping a lot of various scripts and implementations
• NaughtyAttributes : A plugin to make custom inspector without making custom editor scripts : a must have
• UnityExtensions : My personnal package of extensions and helpers that I use on every projects