Calling a global variable from an actor?

Hello everyone! I recently started with unreal C ++ and want to know how I can call a public variable from a character class of an actor, for example: My character shoots and runs out of ammo, I want him to take a box of ammo and get the full charger .
I have read a lot of posts on this topic, but 90% is for BP and 10% I could not understand very well. Thank you very much!

If you want there’s the code:
[SPOILER]
.H


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

#pragma once

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

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

	// Called when the game starts or when spawned
	virtual void BeginPlay() override;
	
	// Called every frame
	virtual void Tick( float DeltaSeconds ) override;

	//Set a box collider
	UPROPERTY(EditAnywhere)
		UShapeComponent* boxCollider;
	//Generate the function trigger enter
	UFUNCTION()
		void OnTriggerEnter(class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult & SweepResult);
	
};


.CPP


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

#include "TDS.h"
#include "AmmoT.h"
#include "MyPlayer.h"


// Sets default values
AAmmoT::AAmmoT()
{
 	// 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;

	//Create the box in fact
	boxCollider = CreateDefaultSubobject<UBoxComponent>(TEXT("BoxCollider"));
	//Attach to the root
	RootComponent = boxCollider;
	//Generate overlap event for the box(trigger enter)
	boxCollider->bGenerateOverlapEvents = true;
	//Link trigger function to the box,when the box hit the player OnTriggerEnter will called
	boxCollider->OnComponentBeginOverlap.AddDynamic(this, &AAmmoT::OnTriggerEnter);
	//Change the scale
	//boxCollider->SetRelativeScale3D(variable or scale x,y,z);
}

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

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

}

//The function where all code will execute when the player collide with the box
void AAmmoT::OnTriggerEnter(class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult & SweepResult) {
	if (OtherActor->IsA(ACharacter::StaticClass())) {//This condition only afect to the player,only execute the code screen message with the player,the character class(not tested with enemies)
		GEngine->AddOnScreenDebugMessage(-1, 15.0, FColor::Yellow, TEXT("Collision"));
	}
}

[/SPOILER]

You can try:
AMyCharacter* myGuy = Cast<AMyCharacter>(OtherActor);

thanx so much!!