function SendEmail(){
  var emailRange = SpreadsheetApp.getActiveSpreadsheet()
    .getSheetByName("HLP REQUESTS").getRange("K:K");

  var emailAddress = emailRange.getValues()
    .flat()           // convert a 2d array into a flat array
    .filter(String)   // remove empty elements from the array
    .pop();           // get the last element from the array

  var message = 'A request has been submitted for professional learning related to an HLP you champion.  Please check the Design Team Notes document in case follow-up is required.';
  var subject = 'HLP Request for Professional Learning';

  MailApp.sendEmail(emailAddress, subject, message);
}