latest work; newest work; most recent work
Refers to the most recent creation of an artist, author, director, etc., such as a book, film, album, or game.
The director's latest work will be released next month.
Have you read this author's newest work?
旧作 means 'old work' or 'previous work', the opposite of 最新作.
Compound of 最新 (latest) + 作 (work).