Original: Kubrick's next film, released in 1975, was an adaptation of William Makepeace Thackeray's The Luck of Barry Lyndon, also known as Barry Lyndon, a picaresque novel about the adventures and misadventures of an 18th-century Irish gambler and social climber.
Simplified: The film was based a book by William Makepeace Thackeray and was about an 18th century gambler named Barry Lyndon.