Compound Meter describes time signatures where the beat sub-divides into three equal parts. The 6/8 time signature is felt with two strong beats on count 1 and 4 with subdivisions between them. Compound meters have a more flowing sensibility to them than 4/4, what you've experienced in this course, so far. Notice how the eighth notes group by beat, and that in 6/8, there are two beats per measure.