Ошибался (ashibálsya) translates to 'I was mistaken' or 'I was wrong'. It's a verb in the masculine past tense, referring to a past mistake or a state of being in error.
In the song, the singer looks back on his first love with regret, admitting, 'Это я дурак, ошибался' (I'm the fool, I was mistaken). This single word powerfully captures the song's entire mood of nostalgic self-reflection and the painful clarity that comes with growing up.
Twin brothers Rauf & Faik kick things off with a mood of pure regret in "Детство (Detstvo)" (Childhood). The track mixes English hooks about wanting to run and hide ("And I wanna hide") with blunt Russian verses where the singer officially calls it quits. He tells his partner to stay quiet and just look him in the eyes: "Теперь прошу ты пожалуйста молчи / Смотри в глаза и ничего не говори" (Now I ask you please be quiet / Look in my eyes and say nothing). He decides their connection is over with "наша речь не о любви" (our conversation is not about love) and tells her to simply run away and forget him ("Просто убегай / И не вспоминай").
What makes the chorus stick in your head is the flash of teenage nostalgia. He looks back at being sixteen years old, exhausted from kissing ("По шестнадцать, устали целоваться"), and remembers his ex taking his t-shirt ("Ты взяла мою футболку"). Then he immediately undercuts the sweet memory by saying it was completely pointless ("в этом нету толку" / there is no point in this). He beats himself up for ever catching feelings in the first place, calling himself a fool: "Это я дурак, ошибался / Зачем я так влюблялся?" (I was a fool, I made a mistake / Why did I fall in love like that?). It is a direct, nostalgic track about teenage romance gone sour.