A new translation is a completely fresh translation into a language that already has Scripture. This is not based on an existing translation, but is a completely new translation, using source texts. 

A revised translation updates a translation that already exists so the language is understandable to the community today.

A first translation is the first time that Scripture is made available in a language. For instance, a first Bible is the first time that language has received the full Bible. A first portion is sometimes the first time a language receives any Scripture at all, but it could also be the first time that it receives an additional portion of Scripture. For example, a language may already have the New Testament, but it then receives the Book of Ruth for the first time.