Jorge Ben (later Jorge Ben Jor) recorded “Mas Que Nada” on his first album in 1963. It's a call to the dance floor: get out of my way, I want to get through, the samba is starting and nobody's going to stop me. The chant at the start, with no dictionary meaning, is pure rhythm.
Sérgio Mendes & Brasil '66 made it a worldwide hit in 1966, and it has been covered countless times since, including a 2006 version with the Black Eyed Peas.
“Mas que nada” is an everyday expression — roughly “no way!” or “come off it!” — and the song is short and repetitive. Listen for the way Brazilian Portuguese sounds “d” and “t” before “i” like “dj” and “tch”.