How can I display the list of available WiFi networks?

Use nmcli dev wifi command. It shows the transfer rate, the signal strength and the security as well.

To scan all networks try using the command sudo iw dev wlan0 scan | grep SSID.

You can find more info here: https://askubuntu.com/a/16588/362944

In Ubuntu 16.04 :

1. Go to /sys/class/net you can see list of folders here.
2. find wireless interface. It has wireless folder. for example in my case is wlp10 you can check it using ls wlp10. if the folder's name different use that folder's name.
3. sudo iwlist wlp1s0 scan | grep ESSID

now from here you can list all available WiFi.
source from here