what is sudo tar -xzf? why it is used?

what is sudo tar -xzf? why it is used?

tar is basically The GNU version of the tar archiving utility for more information on tar got to the terminal and type
man tar
You will find out what exactly xzf is used for. Basically they flags (options) when you run a tar command.
[-]x --extract --get: -z --gzip: -f --file F:
The order of this command does matter though.
Basically your command sudo tar -xzf utorrent-server-3.0-ubuntu-10.10-27079.tar.gz will extract the tar.gz archive that you specify as (utorrent-server-3.0-ubuntu-10.10-27079.tar.gz) and will do so as root privileges.