$ sudo apt-get update
$ sudo apt-get install hunspell-fr-classical 

hunspell-fr-classical is installed in your system.

Make ensure the hunspell-fr-classical package were installed using the commands given below,

$ sudo dpkg-query -l | grep hunspell-fr-classical *

You will get with hunspell-fr-classical package name, version, architecture and description in a table

hunspell-fr-classical package basic information: