Immediate
Instant
adverb
If you see 即 before a word, you know that it's probably something that happens really fast or instantaneously. That's why this is immediate or instant.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
すごく可愛いテディーベアを見つけたので、即買いしちゃいました。
I found a super cute teddy bear and immediately bought it.
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.