The exact original recording behind this clip is not documented, so it is best understood as a user-generated soundboard meme built around everyday Indonesian slang. Bener banget means really true, and bos is a casual way to address a friend, which together make the phrase a playful way to say you completely agree. Online it circulates as a short reaction sound for edits, streams and group chats, where its repeated chant format makes it instantly recognisable even to viewers who do not speak Indonesian.