Complex sentence: Duple meter is a meter in which each measure is divided into two beats, or a multiple thereof (quadruple meter), for example, in the time signature 2/4, each measure contains two (2) quarter note (4) beats.
Split into simpler sentences: Duple meter is a meter in which each measure is divided into two beats, or a multiple thereof (quadruple meter). For example, in the time signature 2/4, each measure contains two (2) quarter note (4) beats.