The translation of the Quran is helpful and encouraged so people who does not understand Arabic could have some understanding of the Quran. With the translation of the Quran the actual miracle of the book is missing because the translator can never do justice to the words of god.
A juz separates the Quran into 30 sections so during the 30 days of Ramadan the nightly prayer can be recited easier. This will briefly explain the Quran which will be sectioned into 30 lectures. Prior to the lecture there will be a recitation of the Quran in arabic.