The batucada is the sound of a Rio samba school's bateria on the Sapucaí: hundreds of drummers behind the samba-enredo. It is written here in cut time, so each half note is one samba beat (half = 130) and the eighths are the samba's sixteenths.
Listen from the bottom up. The surdo de segunda answers on beat 1 and the bigger surdo de primeira lands on beat 2, the heavy one the whole parade walks on. The surdo de terceira (cortador) cuts across them with off-beat strokes. Over that the caixa rolls every sixteenth with accents on the last sixteenth of each beat, the chocalho shakes the same grid leaning on the off-beats, and the tamborim and agogô carry the short syncopated phrases that give each school its signature.
Practice hint: mute everything but the two low surdos and walk to beat 2, then add one voice at a time.