Chord II and 1st inversion
In a major key, chord number two tends to be a minor chord. To explain, let's look at the scale below:
Chord II in a major key is a minor chord. This is because the note which tells us if a chord is a major or minor (the 3rd) in this case, is a minor 3rd.
Look at the scale of C major. We already know that chords 1,4 and 5 are major chords because they contain major 3rds. Chord 6 is a minor because it contains a minor 3rd.
When we play the above chord with the D as the lowest note, we say that it is a D minor chord in root position.
If we moved the position of the chord so that the F was the note at the bottom of the chord, and the other two notes (in this case A & D) were on top, we would say that this is a D minor chord in 1st inversion.
1st inversion is when the chord is positioned so that the 3rd of the chord is the lowest note.
How to form and play inversions of chords