Error 2664 cannot convert argument 2 from

Your problem is that you are trying to assign a newly defined delegate to an already defined one, one that is expecting different parameters than your newly defined delegate. In order to assign a delegate to your componentbeginoverlap, you should be using a function that has the following parameters;

onCollide(class UPrimitiveComponent* OverlappedComponent, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult & SweepResult);

You don’t need a redefinition. Just use the one that already exists.

I know that this error occurs when unreal can’t convert from one variable type to another. I also know that my current data type is void, but what am I supposed to convert this void to?

XD.cpp
// Fill out your copyright notice in the Description page of Project Settings.

#include "Test2.h"
#include "XD.h"

// Sets default values
AXD::AXD()
{
 	// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
	PrimaryActorTick.bCanEverTick = true;

	newMesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("Static Mesh"));
	newBox = CreateDefaultSubobject<UBoxComponent>(TEXT("Collision Box"));
	newBox->OnComponentBeginOverlap.AddDynamic(this, &AXD::onCollide);
}

// Called when the game starts or when spawned
void AXD::BeginPlay()
{
	Super::BeginPlay();
	
}

// Called every frame
void AXD::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);

}

XD.h:

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "GameFramework/Actor.h"
#include "XD.generated.h"

#define DECLARE_DYNAMIC_MULTICAST_DELEGATE(a);
#define DECLARE_DYNAMIC_MULTICAST_DELEGATE(b);
#define DECLARE_DYNAMIC_MULTICAST_DELEGATE(c);

UCLASS()
class TEST2_API AXD : public AActor
{
	GENERATED_BODY()
	
public:	
	// Sets default values for this actor's properties
	AXD();

protected:
	// Called when the game starts or when spawned
	virtual void BeginPlay() override;
	UFUNCTION()
	void onCollide(UPrimitiveComponent* a, class AActor* b, class UPrimitiveComponent* c)
	{
		Destroy();
	}

public:	
	// Called every frame
	virtual void Tick(float DeltaTime) override;
	UPROPERTY(EditAnywhere)
	UStaticMeshComponent* newMesh;

	UPROPERTY(EditAnywhere)
	UBoxComponent* newBox;
	
};