What is this 'runway number' automatic readout system on a flight deck?
That's indeed the plane. It's equipped with a RAAS (Runway Awareness and Advisory System).

It also provides other call-outs, such as remaining runway length, approaching a runway, being on a runway, staying for too long on a runway, among others.

It is indeed a safety system, to make sure runways are not mixed up, and awareness of being on a runway in low visibility, for example. It is not standard on all planes, for example from the linked article:


  In 2015 the largest European low cost carrier Ryanair announced it would equip their entire fleet by the end of 2016 with RAAS as an investment in its commitment to safety.


The system does not require airport equipment, it requires a software update to the plane's EGPWS and the on board GPS. If an airport is not in the EGPWS database, such as some of the infrequently used GA airports, the system won't be able to call-out the runways.

The system was certified in 2007, but I haven't been able to confirm the entry into service date, but it's been around for a while. According to the Wikipedia link, Alaska Airlines introduced it in 2008.