Hi Bboo7,
Welcome to our community! 
Thanks for sharing the screenshot. That’s helpful. In this case, the error message tells us what the problem is: There is a name conflict.
According to the error message, you have System.Threading.Timer and UnityEngine.Timer in the scope of your class. The class we wrote is UnityEngine.Timer.
Check the top of your code. Maybe the System.Threading namespace was added there. Visual Studio Code sometimes adds namespaces there, which could result in a conflict. Remove using System.Threading; from your class, and save your script.
Remember you can also look at the lecture code changes via the link in the Resources of each lecture.
Did this fix it?
See also:
- Forum User Guides : How to mark a topic as solved