Error when retrieving the variables of my emails

Hello good afternoon, I have developed a method that allows me to issue emails to identities that I can select from a form of aras. . I apply a method in a workflow activity that allows me to send emails to identity A, and that email must contain the number of "_item_number" that corresponds to a folio, to place it in the mail body, however I can not recover it and the email appears blank, how could I retrieve values directly from the item to my email?