Arpeggios are the notes of a chord played one after another rather than ringing out together. The great advantage of using arpeggios in your improvisations is that you can directly spell out the chord changes (and always sound good), or add more colour by superimposing an arpeggio over a different chord type. In the key of C major there are two major 7th chords, three minor 7th, one dominant 7th, and one minor 7b5 chord.
C major7, D minor7, E minor7, F major7, G7, A minor7, and B minor7b5.
The chart below shows an example of each arpeggio type with the root on the 6th string.