How can i solve this error?because i am doing the right things

There are a few problems with the script:

 health = Mathf.(lamp(health, 0.0, 100.0);
 hunger = Mathf.(lamp(hunger, 0.0, 100.0); 

Replace (lamp with Clamp..

 health = Mathf.Clamp(health, 0.0, 100.0);
 hunger = Mathf.Clamp(hunger, 0.0, 100.0); 

Next one is the function name, it is case sensitive:

 function OntriggerEnter (other : Collider)

should be:

 function OnTriggerEnter (other : Collider)

And third:

 Destroy(other.gameObject.transform.parent.gameObject);

This is not really an error, but it included an unnecessary step

 Destroy(other.transform.parent.gameObject);

There's another problem though, which you should fix yourself: your health will get reduced to 0 very fast because of this little piece:

 if (hunger <= 5)
 {
     health--;
 }

Look at what you did with hunger, and do the same to health (hint: deltaTime)

The end result:

 #pragma strict
 
 var health : float = 100.0;
 var hunger : float = 100.0;
 
 function Start()
 {
 
 }
 
 function Update()
 {
     hunger -= Time.deltaTime * 0.33;
 
     if (hunger <= 5)
     {
         health--;
     }
 
     if (health <= 0)
     {
         print("Moriste!");
     }
 
     health = Mathf.Clamp(health, 0.0, 100.0);
     hunger = Mathf.Clamp(hunger, 0.0, 100.0);
 }
 
 function OnTriggerEnter(other : Collider)
 {
     if (other.gameObject.name == "Banana" && hunger <= 90.0)
     {
         health += 10;
         Destroy(other.transform.parent.gameObject);
     }
 }

trying adding the "C" to your mathf.lamp statements.. you have ...

      health = Mathf.(lamp(health, 0.0, 100.0);
     hunger = Mathf.(lamp(hunger, 0.0, 100.0); 

when you should have...

  health = Mathf.Clamp(health, 0.0, 100.0);
 hunger = Mathf.Clamp(hunger, 0.0, 100.0); 

hope that helps bud

take care Gruffy