That’s an Openreach ONT ( optical network termination ) and if the lights are steady green, ready for BT to accept an order from you to provide a FTTP broadband service over it, as it’s fibre to the premises very fast speeds are available ( probably 900Mb ) but other slower speeds are available too…as you have posted on a BT customer forum, presumably you will be ordering with BT , your address should should show you as having ‘full fibre ‘ available if you order on line, otherwise , as suggested call the FTTP team ( not the regular customer service people ), you don’t need any ‘line’ providing or engineer visit, the address is ‘ready’ simply order and connect the router when it arrives
