What exactly don't you understand - what to do, or how to read this (with the number behind brackets e.d.)
If I write out what I would do for the smallest size, might that help?
Decrease 1 stitch at the neck edge (where the neck is going to be), BUT only in the 2nd row, then the 3 following alternate rows. So I'd say row 4, row 6 and row 8.
Then every following 4th row (row 12, 16, 20 e.d.) till you only have 22 stitches on your pen, ending with the right side facing for the next row.
Or are you maybe mainly wondering how to decrease?