These slightly discordant chords add a sense of urgency to what is otherwise just an A minor strum.
All I'm doing here is strumming along on the A minor then putting in a "fill" by going to an open C, holding the shape, moving up 2 frets, moving up another fret - back to A minor.
The technical names for the chords marked above the tab as C - D - D# would be ; C - ; D (add9 add11) - ; D# (add b9 ) - but you really don't need to know this.
The point of this lesson is to illustrate how you can use simple chord shapes in unexpected ways to add "flavour".
So hey make up your own!
If you want to play along this is a looped version of the soundfile