Pocket Academy ZERO is a school managing sim; predecessor of Pocket Academy (largely the same, but with ZERO having less content). In Japan what was released as Prestigious Pocket Academy 2 was release as "Pocket Academy" in English, since Kairosoft didn't release the first version (Prestigious Pocket Academy 1) in English until many years later (as Pocket Academy ZERO).
Language packs are community made translations of a specific game into a language not otherwise supported by Kairosoft. If you wish to create one, you can download the english CSV file here. See the language packs page for details.