A C Major chord contains the notes C, E, G. It is built from the major formula 1 - 3 - 5, with C as the root.
Is C major a good first chord to learn?
Yes. C major is one of the most common first full chords, because it uses three fretted notes alongside two open strings rather than requiring a barre. Its main challenge is arching the fingers enough to let the open strings ring cleanly.