Reddit mentions of C# 5.0 Unleashed

Open these in tabs, and leave them open. Spend your bored time reading around.

https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/language-specification/introduction

https://docs.microsoft.com/en-us/dotnet/api/?view=netframework-4.8

Buy this:

https://www.amazon.com/C-5-0-Unleashed-Bart-Smet/dp/0672336901/ref=sr_1_1?keywords=c%23+5.0+unleashed&qid=1565226579&s=gateway&sr=8-1

It's a little old now, but the only .net book I recommend. Old means it's cheap. De Smet is a treasure, and his book will give you a solid foundation that no other book I'm aware of will. It's an unapologetic programming book that will take you from basic to advanced in a logical progression. Some stuff has been added since 5.0; you can learn about that stuff on MSDN.

Download visual studio 2019 community and get practicing. Spend a lot of time practicing. However much time you are spending practicing isn't enough; you should be practicing more. This process will change your brain, that takes a lot of exposure, and a lot of active application. Watch a documentary about ballerinas... you should be practicing that much. STOP LOOKING AT STACK OVERFLOW. Look at MSDN. MSDN is documentation, stack overflow is not. NEVER copy and paste code. ALWAYS retype if you need someone else's code. Think about everything you're typing, look up what you don't understand on MSDN, and read until you understand. Come up with ideas, and try them out. Microsoft often provides a lot of ways to do the same thing, try them out to figure out how they are different. Explore the space. Revisit your old projects every 6 months or so so you can make fun of yourself and re-write them with what you've learned since then. Oh, and practice a lot.

Please show your copy of the book to your future CS professor, so they can compliment my recommendation. Give the book away to someone starting out when you don't need it anymore (it will be a while).

Free:
Microsoft Virtual Academy (not bad, depends on a course),
Channel 9

Paid but with free trial:
Pluralsight.com(the best!),
Udemy,
Wintellect.com

Books:
IMO, the best for beginners C# 5.0 Unleashed by Bart De Smet
https://www.amazon.com/C-5-0-Unleashed-Bart-Smet/dp/0672336901

then:

C# book: C# in Depth by Jon Skeet
.Net book: CLR via C# by Jeffrey Richter

And there is always StackOverflow.com

I'd recommend C# 5.0 Unleashed (https://www.amazon.com/C-5-0-Unleashed-Bart-Smet/dp/0672336901/). It might look daunting, but if you're serious about learning C#, I think this is the one to get, because it not only teaches you the language, it explains why it is the way it is, which I think is an excellent way to deeper understanding. Depending on the version of Unity you're using, and your target platform / scripting backend, you might not be able to take advantage of everything C# 5.0 has to offer. And 5.0 is not even the latest version of the language. That aside, this book is excellent.

What it doesn't do, though, is walk you through projects, in a let's-build-this-game-step-by-step kind of way, which as others wrote might be helpful at first. I'd still recommend you buy this book and use it to read about the interesting details of whatever you learn elsewhere or through tutorials.