I should start by defining what firmware is. Firmware is the low-level software that controls a device's hardware. Updating it can fix bugs, improve performance, enhance security, add features, etc. That's a standard explanation, so including that makes sense.
Note: Replace "d01g" with your actual device model for the most relevant information. d01g firmware updated
Also, possible common questions they might have, like what happens if I don't update, or how long the update takes. Answering those could be useful. I should start by defining what firmware is