Please help me, the question is below:
Which programming language do I need for Unreal Engine 4?
You need c++, inside visual studio
UE4 got blueprints which only requires from you logical thinking and knowing ue4 game play framework as it simple graph which is quite easy to understand. Other then that gameplay can be coded in C++ too, C++ gives runs directly on CPU and full access (Almost as some modules don’t expose everything) to engine APIs. Blueprints usually sufficient to game play programming, or else you so something outside of the box, that for example involved file system, advance networking or heavy ticking or extending capabilities of engine it self.
In first case to learn the principles of UE4 you should use the Blueprints in the Engine. Later on use C++ to speed up your game