I want to learn c# for Unity to make an FPS game but I don’t know where to learn. What I have been using does not apply to Unity. Is there a place I can learn? And how long does it take?
You can try here: Learn game development w/ Unity | Courses & tutorials in game design, VR, AR, & Real-time 3D | Unity Learn
and/or here: http://learncs.org/
The large majority of (any) C# resources that you find online should be applicable in Unity. Definitely begin from the bottom and work your way up. I believe the resources in the link provided will do that, too.
There’s no concrete time frame on how long it will take, as that depends on you. When you get started, begin reading and practicing, you will get a feel for how it’s going.
What were you using?
I was using SoloLearn to learn c#
Okay, I looked that up and although I didn’t open the lessons, the topics seem “correct”. The large majority of that should be usable inside Unity.