$ sudo apt-get update
$ sudo apt-get install libxml-namespace-perl 

libxml-namespace-perl is installed in your system.

Make ensure the libxml-namespace-perl package were installed using the commands given below,

$ sudo dpkg-query -l | grep libxml-namespace-perl *

You will get with libxml-namespace-perl package name, version, architecture and description in a table

libxml-namespace-perl package basic information: