Juízo can mean 'judgment', 'sense', or 'sanity'. It's a word that often appears in expressions related to losing one's mind or acting irrationally.
In this song, the lyric "Vou perder o juízo" (I'm going to lose my sanity) perfectly captures the intense, almost overwhelming feeling of being consumed by love and longing. It's a dramatic and relatable expression of how love can make you feel like you're losing control.