firefox-esr-l10n-xh software package provides Xhosa language package for Firefox ESR, you can install in your Debian 8 (Jessie) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install firefox-esr-l10n-xh
firefox-esr-l10n-xh is installed in your system.
Make ensure the firefox-esr-l10n-xh package were installed using the commands given below,
$ sudo dpkg-query -l | grep firefox-esr-l10n-xh *
You will get with firefox-esr-l10n-xh package name, version, architecture and description in a table
| Distro | Debian 8 jessie |
| Section | Language packs |
| Package | firefox-esr-l10n-xh |
| Version | 45.5.0esr-1~deb8u1 |
| Description | Xhosa language package for Firefox ESR |
| Sub Section | localization |