Labels

Pivot has a concept of labels. A label is simply the value that is shown after data has been filtered. By default, every field is labelable. To access said labels:

pivot.display().rowLabels().set(['last_name'])

// which creates an object that you can view with pivot.display().rowLabels().get:

pivot.display().rowLabels().get;
//> Object
// >last_name: Object
// >__proto__: Object

In table you'll use the labels to display your filtered fields. Once again I reccomend reading the spec for more details.