What languages would you need for working with the likes of Unity or Unreal?

Answer 1

Unreal/C++:
https://www.sololearn.com/Course/CPlusPlus/
www.UnrealEngine.com

Unity/C#:
https://www.sololearn.com/Course/CSharp/
www.Unity3D.com/learn

Answer 2

Thank you very much Fata1 Err0r