This song is played with a type of rhythmic groove call Swing.When playing music with a swing groove (or feel), you do not play the eighth notes with the same straight rhythm that you're used to. Rather, in a swing, the first eighth note in a pair is approximatly twice the duration of the second eighth note in that pair. One way to help understand this rhythm is to play eighth note triplets where the first note within each triplet is a quarter note. There is an example of this attached. The easiest way, however, will be to find and listen to examples of swing rhythm, and let your ear guide you!
Heart & Soul is a classic piano duet tune. One player performs the melody in the treble clef, and the other player performs the accompaniment in the bass clef, all on the same piano!