In the following example, you will notice some divided chord symbols. These symbols indicate a chord with a specific bass note under it. and are called slash chords. E.g. in bar 2, the chord symbol G/B occurs. This indicates a G chord played over a S bass note.
In bar 4, the symbol G/D indicates a G chord with a D bass note. In bar 5, the symbol Am/E indicates an A minor chord with an E bass note. Slash chords are often used to create smooth, melodic bass lines and the symbols tell you that a note other than the root is played as the bass note of the chord.
Slash chords can create many different harmonic effects. Each combination has a specific name and often creates an entirely new chord. Basically you can play any chord over any bass note as long as it sounds good. Experiment with playing all the chords you have learnt over various bass notes from the scale of the key you are playing in.