trigger accountTestTrggr on Account (before insert, before update) {
 
   List<String> accountNames = new List<String>{};
  
   //Loop through all records in the Trigger.new collection
   for(Account a: Trigger.new){
      //Concatenate the Name and billingState into the Description field
      a.Description = a.Name + ':' + a.BillingState
   }
    
}