apertium-pt-gl software package provides Apertium translation data for the Portuguese-Galician pair, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install apertium-pt-gl
apertium-pt-gl is installed in your system.
Make ensure the apertium-pt-gl package were installed using the commands given below,
$ sudo dpkg-query -l | grep apertium-pt-gl *
You will get with apertium-pt-gl package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Miscellaneous |
| Package | apertium-pt-gl |
| Version | 0.9.2~r57551-2 |
| Description | Apertium translation data for the Portuguese-Galician pair |
| Sub Section | Miscellaneous |