Now that the export from translatewiki.net with https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/459274/ has happened:
This does not require you to speak that language. This task is about MediaWiki core.
Add the Eastern Pwo language to the list of languages found in languages/data/Names.php, and then add a file in languages/messages/ that gives information on how to treat the language (such as the fallback language and directionality).
This is important so that MediaWiki knows what languages are available and how to handle them. The Wikipedia article on Eastern Pwo would be useful.
There is no prerequisite knowledge needed for this task.
You are expected to provide a patch in Wikimedia Gerrit. See https://www.mediawiki.org/wiki/Gerrit/Tutorial for how to set up Git and Gerrit.