The G fifth chord is a 2-note chord consisting of the notes G and D.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as G5.
Chords that are a superset of G5. The chords include more notes but always G and D.
In case you prefer a non-interactive variant of the chord chart, we've embedded a PNG image below that shows the notes for the the G5 chord. Feel free to save or share the image as needed.