What does 光年 mean?
光年 is a Japanese noun meaning “light-year” in English. It is written as 光年 in kanji, こうねん in hiragana, and kounen in romaji. This word is part of JLPT N1 vocabulary.
Example sentence
この世界は、あなたたちの住む世界から遥か３億光年離れた位置にあります。
This world is a distant three hundred million light years away from the world where you live.