That sounds like you are getting FTTP. For the broadband the first piece of your equipment will be a new BT SmartHub assuming you are willing to use one rather than what you have.
If the specific BT Product you clicked on, assuming you ordered online, referred to Digital Voice, then the whole copper side becomes redundant, with AIUI your number being retained. If it referred to (IIRC) Standard Voice you will retain the existing landline phone service. Your order confirmation email I expect will tell you.
The powered box she referred to will be mounted on a wall near to an existing power socket, to some extent at a place of your choice. It's an ONT (Optical Network Terminator) as Andrew said, converting the optical signal to ethernet as a normal modem converts an analogue one.
My broadband basic info/help site - www.robertos.me.uk.
Domains, sites and mail hosting - Tsohost
Connections: OnePlus 8 Pro max 165Mbps down, 24Mbps up on Three, and B311 4G, tbb tests normally 35-45Mpbs down, 65Mbps off-peak, 9-24 up.
To argue with mindless bigots is foolish.
Edited by RobertoS (Thu 15-Oct-20 01:03:22)