This is a WiFi Card, however, I'm not certain that your friend's DS ever had it? It seems odd to me. But I also don't see the socket that it would have plugged into. It looks like it might be a different variant? What is the model number of the console?
You can see a better picture of the part in question removed from the board [link|https://www.sosav.com/guides/game-consoles/nintendo/nintendo-portable/nintendo-2ds/wifi-card/|at this guide|new_window=true] in steps 9 and 10.