If you click on the learn more option it will take you to a page that details all the updates (usually bug and security fixes) since JDK 8 was released. What this is referring to is Java SE 8u221 or Java Standard Edition update 221. Theres quite a bit going on here so lets take the time to explain.
You should see a section on the page similar to the below. Navigate to and scroll down till you get to the Java SE 8 version.
