Sometimes you’ll see a chord with the number 5 after it. What does that mean?

Normally the A chord is made up of the 1st, 3rd, and 5th steps of the major scale (A, C#, E).

With an A5 chord, you’ll drop the 3rd and only play the 1st and 5th (A, E).

This is effectively a power chord and sounds great turned up with a lot of distortion, so you’ll hear it a lot in rock and metal music.