Achterbahn literally translates to "figure-eight track", which is the German word for "rollercoaster". It's a fun and evocative word that immediately brings to mind excitement and ups and downs.
In the song, Beatrice Egli uses it to describe intense emotions, singing "Und unsere Gefühle, die fahren Achterbahn" (And our feelings, they ride a rollercoaster). This metaphor perfectly captures the thrilling and unpredictable nature of the feelings she's experiencing, making it a memorable and engaging word choice.
This is a song about grabbing a good moment while it lasts. Beatrice Egli opens with "Das ist der Moment / In dem alles stimmt" (This is the moment / In which everything is right), and the feeling is light enough to fly "Wie ein Schmetterling" (Like a butterfly). The happiness wasn't planned either: "Wir haben ihn nicht gesucht / Und doch gefunden" (We didn't look for it / And yet found it).
Then the chorus turns the volume up, literally. "Wir leben jetzt / Wir leben laut / Wir wollen mehr / Wir drehen auf" (We live now / We live loud / We want more / We crank it up). The second verse brings the bigger images, a "Tanz auf dem Vulkan" (Dance on the volcano) and feelings that "fahren Achterbahn" (ride a rollercoaster), and she says they have already "das große Los ... gezogen" (drawn the big prize). With "Für uns gibt es kein Zurück" (For us there's no turning back) on repeat, it's a party song with one clear message: this is your shot at happiness, so take it.