using System;

public class Program

{

    public static void Main()

    {

                                        public class Explosion : MonoBehaviour

                    {

                        void Update()

                        {

                            if (Input.GetKey(KeyCode.Space))

                            {

                                Destroy(gameObject, 2);   // The number is the amount of seconds

                                Debug.Log("BOOOOM");

                            }

                        }

                    }

​

    }

}