Player.cs

using System;
using UnityEngine;

public class Player : MonoBehaviour
{

    [SerializeField] private float speed;
    [SerializeField] private float horizontalInput;
    [SerializeField] private float verticalInput;

    /*
    private void OnCollisionEnter(Collision other)
    {
        throw new NotImplementedException();
    }
    */

    private void OnTriggerEnter(Collider other)
    {
        if (other.CompareTag("Diamond"))
        {
            speed++;
            print("Diamond Collected");
            Destroy(other.gameObject);
        }
    }

    void Update()
    {
        Controls();
    }

    private void Controls()
    {
        horizontalInput = Input.GetAxis("Horizontal");
        verticalInput = Input.GetAxis("Vertical");
        //  new vector3(-1,0,0) * 5 * real time
        transform.Translate(new Vector3(horizontalInput,0,verticalInput) * speed * Time.deltaTime);
    }
}

/* Thankyou Baccho */