lo: no wireless extensions enp9s0: no wireless extensions
lspci | grep Network
0c:00.0 Network controller: Broadcom Inc. and subsidiaries BCM4312 802.11b/g LP-PHY (rev 01)
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Many Broadcom wireless adapters require proprietary firmware not included with the Archiso. It is going to be easiest to complete the installation with an Ethernet cable connected if you can manage that, but make sure to install the appropriate firmware package from the AUR when you are installing Arch.
See the kernel wireless wiki for details on identifying which firmware you need.
If you are relying on a WiFi hotspot from your smart phone you could try using USB tethering from Android or iOS instead. This will create an Ethernet interface and allow accessing the smart phone's data connection.
You can connect to available Wifi network using Network manager.
Is Network Manager installed? You install it during the installation of Arch Linux. If not, install it. If you don't have an Ethernet connection, it won't help you.
pacman -S wpa_supplicant wireless_tools networkmanager
Enable the Network Manager.
systemctl enable NetworkManager
Start Network Manager.
systemctl start NetworkManager
List nearby networks.
nmcli device wifi list
You should be able to see a list of available networks nearby. Connect to a nearby network. SSID - Name of Wifi Network. SSID_password - Password of Wifi Network.
nmcli device wifi connect SSID password SSID_password