The Hidden Label Field allows you to get the label corresponding to the value of another field.
Say you have a select field where you choose the Pizza flavor and is associated with its price:
Margherita|10
Pepperoni|12
Potatoes|12
If Pepperoni is selected, as to form data you would get back 12, but you have lost the name of the selected flavor! The Hidden Label solves the issue: Create a new Hidden Label with the name flavor_label and set the id of the field you want to get the label from, in this case, flavor.
Now you are able to write "You selected a Pepperoni pizza at a price of $12" using these tokens:
You selected a [form:flavor_label] pizza at a price of $[form:flavor].