This is a relatively basic arrangement of the traditional carol, O Christmas Tree.
The melody dates back to the 17th century and is simply a sixteen measure progression following the A-A-B-A form. It is in 3/4 time and played with a swing feel.
I have added a little jazzy intro and outro and the lesson includes a bit on extending it with your own variations.
There are quite a few barre chords and being able to roll or arpeggiate full chords will help create a very nice feel.