Implementation depends on what enum you use.

If you want to use an Unreal Reflection System-friendly solution that uses UENUM, there is a ready-made function for this:

// Header file

// This is your enum
UENUM()
enum class EnumExample : uint8
{
	EnumValue1,
	EnumValue2
};


// Implementation file

// This is how you get the string representation of the enumerator
FString StringRepresentation = UEnum::GetValueAsString(EnumExample::EnumValue2);

If you want to use a pure C++ solution, you should create a function to manually convert the enumerator. For example like this:

// Header file

// This is your enum
enum class EnumExample : uint8
{
	EnumValue1,
	EnumValue2
};

class AnyClass
{
public:
	static constexpr const TCHAR* EnumToString(EnumExample Enum);
};


// Implementation file

constexpr const TCHAR* AnyClass::EnumToString(EnumExample Enum)
{
	switch (Enum)
	{
	case EnumExample::EnumValue1:
		return TEXT("EnumValue1");
	case EnumExample::EnumValue2:
		return TEXT("EnumValue2");
	default:
		return TEXT("Invalid");
	}
}

// This is how you get the string representation of the enumerator
FString StringRepresentation = EnumToString(EnumExample::EnumValue2);