Cooldown/Timer system (Javascript)

Hi everybody, so yeah i need to get a working timer/cooldown function for my tree "harvesting" system. I want the cooldown to be 10 seconds and to function like this : I can harvest the tree once and then i need to wait 10 seconds so i can harvest it again and so on so on... But i cannot find a way to create that kind of a system and all of the other answers i've seen on other posts have not worked (Could be that i did something wrong tho). But yeah if anyone can help me i would really appreciate it!

My code =

 #pragma strict
     
     var TreeHarvest : boolean = false;
     var menuSkin : GUISkin;
     public var Player : GameObject; 
     private var InventoryScript : Inventory;
     private var ExpScript : ExpSystem;
     var canHarvest : boolean = false;
     
     function Start () {
     
     }
     
     function Update () 
     {
     
     }
     
     function HarvestTree () 
     {
         InventoryScript = Player.GetComponent(Inventory);
         InventoryScript.wood += 1;
     
         ExpScript = Player.GetComponent(ExpSystem);
         ExpScript.Exp += 1;
     }
     
     function OnTriggerEnter (other : Collider)
         {
             if(other.tag == "Tree") {
                 TreeHarvest = true;
             }
     }
     
     function OnTriggerExit (other : Collider)
     {
         if(other.tag == "Tree"){
             TreeHarvest = false;
         }
     }
     
     function OnGUI ()
     {
         if(TreeHarvest == true)
         {
             GUI.skin = menuSkin;
             GUI.BeginGroup(new Rect(Screen.width / 2 - 150, Screen.height / 2 - 150, 300, 300));
             GUI.Box(Rect(0, 0, 300, 300), "Tree Harvesting");
     
             if(GUI.Button(Rect(60, 50, 20, 20), "Harvest Tree" ))
             {
                 if(canHarvest == true) {
                     HarvestTree();
                 }
             }
         }
     }