$ sudo apt-get update
$ sudo apt-get install libgnutls-xssl0 

libgnutls-xssl0 is installed in your system.

Make ensure the libgnutls-xssl0 package were installed using the commands given below,

$ sudo dpkg-query -l | grep libgnutls-xssl0 *

You will get with libgnutls-xssl0 package name, version, architecture and description in a table

libgnutls-xssl0 package basic information: