How do I sniff all the wifi signals using wireshark?

First you have to put your wireless device(for example wlo1 here) into monitor mode using:

sudo ip link set wlo1 down
sudo iwconfig wlo1 mode monitor
sudo ip link set wlo1 up

RFKILL error

You may come across a RFKILL issue when trying to use sudo ip link set wlo1 up There is a workaround for this covered here

Then run wireshark as root so it can sniff wlo1

sudo wireshark

#wireshark