I did not find any official bbPress downloads for the Portuguese language. I found in Google all kind of suggestion but I believe it is for old versions of the bbPress plugin.
I have already installed it and it is fully functional, but the .po / .mo files are missing. If not, how do I translate the plugin?
If you already have an account on link use it otherwise, create one and log in.
Then download the files .po and .mo , version 2.4 or later at link .
FIX: The correct link is link as commented on by @brasofilo. The link to version 2.4 that appears on the bbPress website is outdated and should not be used!
Assuming the files have been downloaded to ~ / Downloads and your site is in ~ / www do:
cd ~/www
cp ~/Downloads/bbpress-dev-pt-br.po wp-content/languages/bbpress/bbpress-pt_BR.po
cp ~/Downloads/bbpress-dev-pt-br.mo wp-content/languages/bbpress/bbpress-pt_BR.mo
# conferindo ...
ls -lA wp-content/languages