When you play triplets in music you're placing 3 notes where there use to be 2. In this 1st example it is a simple eighth note count (the red dots represent the beat and the red outlined dots represent the half beat).
The next example is dividing each beat into 3 counts. Try to count a long with it, like this (1 2 3 1 2 3 1 2 3 1 2 3).
To count this correctly we use the example below,
(1 ah and 2 ah and 3 ah and 4 ah and). Now you are counting in triplets.