The term "update field" refers to a type of step that can be incorporated into your automation. The update field step is unique as it allows you to change a contact record based on behavior in the automation. Update Field will add a value to a contact’s demographics or add them to a category defined in the step.
Drag the Update Field step over to the desired section of your workflow. Click the pencil to edit step:
You can update more than one field in this step, simply click "Insert Field" again.