Quick question about the Stripe Cashier doc regarding event please

Hi all,

I have never used cashier with Laravel and would like to enquire about this section please: https://laravel.com/docs/8.x/billing#syncing-customer-data-with-stripe

it says:

To automate this, you may define an event listener on your billable model that reacts to the model's updated event. Then, within your event listener, you may invoke the syncStripeCustomerDetails method on the model:

Could someone give me an example of this please as I am not understanding this part. Where is the billable model coming from?

Thanks