At a guess, thats a USB stick and a USB port in that symbol. I think your telly is saying that it needs a firmware update. Go online, search for your tv model in the OFFICIAL Samsung website (do NOT download from any 3rd party website!), follow the instructions for extracting any firmware update, including how to put it onto a BLANK, FORMATTED USB stick. Once you've done this, safely remove the USB stick, then insert it into the USB port (typically, on the back of the tv, beside the hdmi ports, etc) with the tv itself switched OFF. Once you are certain you have correctly inserted the USB stick, POWER ON your tv. Your tv should then automatically check the firmware is a more recent version than what is already on it, then start updating it. You might need to refer to your instruction manual or, if you don't have it to hand, the Samsung website should have a pdf copy of it on their website. If all is good, switch OFF the telly, remove the USB stick, then power up the TV as normal.
As an aside - if yours is a SMART TV, with an Ethernet cable plugged in between your tv and your Internet router, you should be able to set up the tv to automatically update the firmware. Again, refer to your tv manual, to learn how to set this up.
