Circle
This radical is the same as the kanji. It means circle.
Just in case you don't remember this, here's the kanji meaning mnemonic: What's something with nine sides? Just add a drop and you'll have something that's almost a circle.
An update is needed before you can continue but you have more than one WaniKani tab open.
Finish up what ever you are doing on the other tab(s), then close them to continue.
The update will complete automatically once the other tab(s) are closed.