Samsung has started to roll out the fifth, and perhaps the final, Oreo beta update for the Galaxy S8 and the Galaxy S8+ in some regions. Users in India are receiving what is being called the second beta, but in other regions, the fifth beta is rolling out.
Both the beta include the same improvements and bug fixes, which means that they’re the same and could be the final one before Samsung starts the official Android 8.0 Oreo rollout. The Indian variants started receiving the beta only recently, which is probably why it’s being called the second beta.
As for the Galaxy S8/S8+ variants in the US, UK, and South Korea, the previous beta was numbered 4. You will receive the new beta only if you have signed up for the Galaxy Beta program and are on the last beta.
The latest beta weighs around 613MB and is software version ZQLE. It is available as an OTA, so make sure you download it over a Wi-Fi connection. You can check for the update manually by heading to Settings > About > Software Update and tap on the option that says Download updates manually.
Samsung should be releasing the final stable Oreo update for the Galaxy S8 and S8+ in January 2018.