An eighth note triplet is a group of three evenly spaced notes played within one beat. Eighth note triplets are indicated by three eighth notes grouped together with the numeral 3 above or below them. The eighth note triplets are played with one third of a beat each. Triplets are easy to understand once you have heard them played.
Once you are confident counting triplets, try moving them around between the snare drum and the toms. Use alternate sticking beginning with the right hand and then reverse them. Then try one hand per drum (LLL, RRR etc)
Now try this one which uses triplets on the bass drum (right foot) and snare drum (left hand) while the right hand plays each beat on the hi-hats. This one is tricky, so take it slowly at first.