Advanced Level, High Grade, Advanced Grade, High Level
noun
When you are at an above rank, you are at an advanced level. This is referring to things like proficiency in Japanese, or things like that.
じょうきゅう
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.
どうしても上級クラスについていけません。
I can't follow the advanced level class.
コウイチは私の学校の上級生です。
Koichi is a senior student at my school.
英語が母国語でない人で、ネイティブレベルや上級の英語を話す人もいれば、そうでない人もいます。
Some non-native speakers speak English at a native or advanced level, while others do not.