eSIM profiles are electronic versions of a physical SIM. Think of a downloaded video vs a DVD. An eSIM can be downloaded over the internet and installed into a device. The most common method of doing this today is via a QR code or through an iOS, Android or a Microsoft Windows application.
The Truphone plan is linked to an eSIM when an order is made via Truphone Connect API. The end user must install the eSIM to then use the service. Once the eSIM has been installed, the partner can make any number of renewals of the same (or other) plans to the same eSIM, meaning that the end customer does not need a new eSIM for each data plan. Visit the Getting a new eSIM to understand how the process works.