Noun and な adjective
きょくたん
君は奇跡を起こすことができるかもしれない。でも、僕は君には極端なことは避けてもらいたいんだよ。
You may be able to perform miracles, but I want you to avoid doing extreme things.
At the extreme edge, which is just the extreme.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.