Firmware updates can significantly improve the recording quality of your recorder and add compatibility for more DVD±RW media. Basically the firmware contains a database of media types and the settings/tunings for the specified media, that the recorder will use as you burn discs.
Typically if the disc is unknown to the recorder, the recorder will apply a generic recording tunings, which often leads to sub-optimal burn quality and/or less than maximum recording speeds.
Usually the firmware update procedure involves downloading a firmware updater software manufacturer, running the updater and rebooting the PC after the procedure is complete.
You can use Nero Info Tool
to check what firmware you currently have.