SendMail.gs

function sendMail() {
  var sheet = SpreadsheetApp.getActiveSheet()
  
  var message = "This week there was " + sheet.getRange("B3").getValue() + " Tiktok views, "
  message += sheet.getRange("B4").getValue() + " Youtube views, and "
  message += sheet.getRange("B4").getValue() + " Skillshare views."

  MailApp.sendEmail("boss@gmail.com", "This weeks views", message)
}

function onOpen() {
  var ui = SpreadsheetApp.getUi();
  // Or DocumentApp or FormApp.
  ui.createMenu('Send Report')
      .addItem('Send to Boss', 'sendMail')
      .addToUi()
    
}