The Book of Ecclesiasticus is one of seven deuterocanonical works that are accepted as canonical Scriptures only by the Roman Catholic Church, Eastern Orthodox Church, Oriental Orthodox Churches and Assyrian Church of the East. They considered non-canonical by most Protestant churches, and are therefore found within only some editions of the Bible. Although the name of this book is similar to that of the well known Ecclesiastes, they are not related.
Deuterocanonical works are a subset of a wider group of books generally classified by most Protestants as apocryphal. They are little known outside of the aforementioned church settings. Apart from them, there are also a list of additional books that are recognised only by the Eastern Orthodox Church and another list only used by the Orthodox Tewahedo (Eritrea and Ethiopia). The Anglican and Lutheran churches generally consider apocryphal books as useful for life instruction but not suitable for the foundation of doctrine.
Ecclesiasticus makes appearances in culture from time to time. Wikipedia lists several, most notably two references from ch.44 found in the film “Chariots of Fire” and on numerous war memorials. A passage from ch.43, v.11-26, was recited in St George’s Chapel, Windsor Castle, at the funeral of the Duke of Edinburgh on 17 April 2021. The Duke was baptised at birth into the Greek Orthodox Church, one part of the Eastern Orthodox Church that affirms the Book to be canonical.