Guitar chords in the key of A:
A Bm C#m D E F#m Abdim

Chord A notes: A, E, A, C# and E. You should not play the 6th string.

The guitar strings 5(A) and 1(E) are left open.

A major chord's alternative names: AM, Amaj, La major, A dur.

Steps: 1-3-5.
1(A), 3(C#/Db), 5(E).