The page shows the systems that haven’t been implemented or completed yet or have been turned off.
Things like FLIR (targeting pod), the laser, datalink, MIDS radios, IFF system, Flight control system A and B for example on your page.
The BIT page itself is bugged though, the RWR and HMD often gets stuck in “restart” and the COM1/COM2 stays inop on the BIT page even though you turned it back on etc. It’s not really useful at the moment.