Progression
The ii–V–I (major) in G major
ii–V–I (major) in G major plays Am7, D7 and Gmaj7 — ii, V and I — across 3 chords. The most common cadence in jazz, moving from a subdominant ii through the dominant V to a resting major-seventh tonic.
The chords, in order
1Am7ii
2D7V
3Gmaj7I