When your unit first turns on, it loads in the firmware (instructions) on how to do everything.
With burners, how-to write particular types of discs is also stored in the firmware.
With DVD reader/writers it is more complex. Thanks to the MPAA's greed the world has been divided into sections called Regions. If a disc is from a different region it might not play back at all.
You can get region free firmwares & can circumnavigate these annoyances with firmware or tools.
However, please post some more info, as the sony should play DVD's fine.