Mistério translates to "mystery". It's an intriguing word that immediately sparks curiosity and makes you wonder what secrets the song holds.
In the context of the song, Jorge Ben Jor sings, "Pois o meu samba tem mistério" (Because my samba has mystery). He's not just talking about a secret, but implying that his samba has a special, captivating quality or a unique rhythm that makes it stand out and is irresistible to dance to.