The music has two, three or four beats in each bar, and each beat is divided into groups of three – you can say 'lollipop' (or 'jiggety' which also ties in the jig) as you listen to compound time music and the three syllables will fit exactly within each beat.
Compound time signatures are written as 6/8, 9/8 and 12/8.
Listen to a jig, the most common dance to use compound time.
Here is a 6/8 march played by a pipe band.
This modern song is in compound time.