"Об" is a preposition in the Russian language that translates to "about" or "concerning" in English. It is used to indicate the subject of discussion or the topic being referred to. For example, one might say "об этом" meaning "about this." In addition to its primary meaning, "об" can also be used in various phrases and expressions. It often appears in contexts involving literature, conversation, or education, helping to clarify what is being discussed. Understanding how to use "об" correctly is essential for effective communication in Russian.