Accents indicate that a note is to be played louder. They are marked by an arrowhead L placed above or below the note, e.g.:
First try all of these exercises on the snare drum only (as written). Once you can play them evenly and smoothly, experiment by playing the accented note on the tom-toms, cymbal, etc. (while still hitting the snare drum), e.g., right hand on the floor tom, left hand on the snare drum, or right hand on the ride cymbal, left hand on the hi-hat.
The possibilities are endless, so be creative and use your imagination.
Accented Triplets eighth notes