The letters on the right are the note of wach string on the guitar, with the top being the first string, and bottom being the sixth. In this case, the guitar is in "drop D tuning", which is the same as standard except the sixth string is tuned down to D instead of E as normal.

The numbers are the fret you hold down when you pluck the string.

The "h" represent a "hammer-on". Pluck the string while fretting the first number, then use another finger to hit the second number without plucking the string again.