$sudo iwlist wlan0 scanning | egrep 'Cell |Encryption|Quality|Last beacon|ESSID'
It’s the combination of
sudo (run as root, do privileged operations),
iwlist wlan0 scanning (produce some output on STDOUT), the pipe symbol “|” (connecting STDOUT of the command(s) to the left to the STDIN of the process on the right), and an
egrep command with a “single quoted” (to prevent the shell from interpreting the “|” characters) Regular Expression to filter STDIN. See
man egrep, and
man re_format for details.