The Micro:bit comes with with pre-installed software
It does the following
Display test
starts with Hello and then a prompt to press button A and then button B
Then ask you to SHAKE
followed by a simple game to chase the flashing dot
NOW GET CODING (ends up flashing various symbols)
Note the sample code also contains Bluetooth functions including Pairing for remote functions and uploading from a Phone or Pad device.
Software can be written and converted into a Hex file that can then be uploaded to the micro:bit
Reinstalling the original BBC sample code
There are a range of programming platforms available for the micro:bit
C++
Block programming is easy to use.