Unity 101 - CoinCollector.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CoinCollector : MonoBehaviour
{
    // A private variable storing the number of coins we've collected
    int coinsCollected = 0;

    // This function is called whenever a game object overlaps a trigger
    void OnTriggerEnter2D(Collider2D collision)
    {
        // Get the game object we overlapped with
        GameObject triggedObject = collision.gameObject;

        // If the game object has the tag "Coin"
        if(triggedObject.CompareTag("Coin"))
        {
// Debug.Log() logs a specific message to the console, helping you keep track of what is going on.
Debug.Log("Coin Collected");

            // Increment coins collected
            coinsCollected = coinsCollected + 1;

            // Destory the game object we overlapped with
            Destroy(triggedObject);
        }
    }
}