translate

using UnityEngine; using System.Collections;

public class NewBehaviourScript : MonoBehaviour {

 float F_time;
 
 void Update () 
 {
     F_time += Time.deltaTime;
 
     if(F_time < 2.0f)
     {
         transform.Translate(Vector3.left * Time.deltaTime);
     }
 }

}

Not a stupid question!

Let's break down your problem a bit, first.

A) I want my object to be translated

B) I want this translation to only last for two seconds.

First, translation is simple:

 transform.Translate(xAmount, yAmount, zAmount);

...Or...

 transform.Translate(vector3Amount);

I prefer the Vector3 version because you can achieve Framerate Independence really easily, as such:

 // Move up 2 units per second, and forward 1 unit per second.
 Vector3 movement = new Vector3(0.0f, 2.0f, 1.0f) * Time.deltaTime;
 transform.Translate(movement);

...Now, let's combine it with that other requirement, that the translation last two seconds:

 public class FooBehavior : MonoBehaviour
 {
     #region Fields/Properties

     public float Duration = 2.0f;
     private float _moveEndsAt = 0.0f;

     public Vector3 Movement = new Vector3(0.0f, 2.0f, 1.0f);

     #endregion Fields/Properties

     #region Engine Hooks

     public void Start()
     {
         _moveEndsAt = Time.time + Duration;
     }

     public void FixedUpdate()
     {
         if(Time.time > _moveEndsAt)
             return;

         Vector3 movement = Movement * Time.deltaTime;
         transform.Translate(movement);
     }

     #endregion Engine Hooks
 }

Pretty much, we just figure out when we want the move to stop (now + duration), and as long as the current time is prior to that ending time, we perform the translation every frame.

Good question, and hope that helps!