Ausersehen means 'chosen' or 'destined'. It's a more formal and poetic word than common synonyms, carrying a sense of fate or predetermination.
In the song, the line "Die für uns ausersehen sind" (Who are destined for us) speaks to the idea of soulmates or people meant to be together. It evokes a feeling of profound connection and the bittersweet realization that such a bond, once lost, may never be found again.
This song tells a story of a huge missed opportunity between two people. It's all about the things left unsaid. One person kept things formal, saying „Sie" (the formal 'you') right up to the end, while the other was waiting and suffering. They both watched each other from a distance, too proud to make the first move: „Kein Wort aus deinem Mund, du hattest Zeit / Kein Ton aus meinem, denn ich hatte Ehre" (Not a word from your mouth, you had time / Not a sound from mine, because I had pride).
They look back on a perfect summer they completely wasted—„Wir haben ihn mit dummer Hand verschwendet" (We wasted it with a foolish hand). Now that the games are over, they realize it was their last chance. The song ends on a deeply sad and final note, suggesting that you only get one shot at meeting the person you're truly meant to be with: „Weil wir nie wieder denen begegnen / Die für uns ausersehen sind" (Because we never again meet those / Who are destined for us).