The phrase 「異世界二度目のおっさんどう考えても高校生勇者より強い」 means "No matter how you think about it, the middle-aged man in another world for the second time is stronger than the high school hero." Breaking it down:
- 異世界 (isekai) = another world
- 二度目 (nidome) = second time
- おっさん (ossan) = middle-aged man
- どう考えても (dou kangaete mo) = no matter how you think about it
- 高校生勇者 (koukousei yuusha) = high school hero
- より強い (yori tsuyoi) = stronger than
It suggests a story or scenario where a middle-aged man who has been transported to another world again is stronger than a typical young hero.
