English translation: Best of its kind/best in its field
Login or register (free and only takes a few minutes) to participate in this question.
You will also have access to many other tools and opportunities designed for those who have language-related jobs (or are passionate about them). Participation is free and the site has a strict confidentiality policy.
@Ysav Boekstaaf: This site is English monolingual and Asker would like to know what the phrase "best in class" means. Fwiw, all languages have monolingual sites for such questions. Does this answer your question?