This Bible book is known by several names. It is called Ecclesiasticus (not to be confused with the canonical book, Ecclesiastes). It is also called "The Wisdom of Ben Sira," or "The Wisdom of Jesus, son of Sirach," and so on. Sometimes it is simply called "Sirach."
Within the book itself, the author declares himself to be Yeshua (Jesus, Joshua), the son of Sira, a Jewish scholar living in Jerusalem. It appears that the book was probably written sometime in the early 2nd century B.C.E. The preface to the book, written by Yeshua ben Sira's grandson, explains that the book was originally written in Hebrew, and that the grandson translated it into Greek. You can read more about the dating of the book in the wikipedia article. There is also detailed information in the Jewish Encyclopedia online and the Catholic Encyclopedia online.
This book is not part of the Hebrew Bible, although it is known in the Hebrew tradition and is quoted in the Talmud. In Protestant versions of the Bible, such as the King James version, it is included with the apocryphal writings.
In Catholic and Orthodox Bibles, however, it is a canonical book, the last of the wisdom books, which appear in this order: Job, Psalms, Proverbs, Ecclesiastes, Song of Songs, Wisdom, and Ecclesiasticus (Sirach).
If you are familiar with the book of Proverbs in the Hebrew Bible, you will feel right at home in Ecclesiasticus, since it has much in common with Proverbs. The book is a collection of ethical teachings and maxims. There is also a long section at the end of the book, beginning with the words "Let us now praise famous men," which offers a history of Jewish heroes, praising all the patriarchs and judges and prophets.
The Greek, Latin and English texts are available side-by-side at the Sacred Texts Archive. I've prepared a script with random quotes from this book of the Bible which should give you some idea about what the book is like (if you are reading this via email or via RSS, you may need to visit the actual blog to see the random quotes):