what is wi-fi?

WLAN - Wireless Local Area Network While WiFi is wireless protocol that connects devices without need of wires. So I'd say Wi-Fi lets you connect to the wireless network. I believe the WLAN option in your mobile is about configuring your mobile to connect to the surrounding wi-fi network. Turn it on and it will detect wi-fi networks around. In order to turn your broadband connection into Wireless Network so that you can connect multiple devices to it - you will need a wireless router. If you don't have one, buy a wireless router and connect it in series with your modem. That is your broadband line will go into the broadband modem and the wireless router will sit between modem and computer.

I hope this clears your doubt. If you have more questions, please feel free to ask 😀