What part don't you understand? Take each st one by one, so on R 1 which is the RS -
p3 k1, move yarn to back and slip 1 st as if to purl, yo (over top of needle and back to WS) k1.
R 2 - p1 k2 p1, move yarn to back of work, slip 1 st as if to purl, take yarn over needle to k next st, p 1
R 3 - same as R 1
It may be that row 4 is what you don't understand -
k1, p2, k1, K st and all yo's tog, - I don't know if the highlighted part should be 'knit that st and all YOs tog' but I think all the YOs from the previous rows are lined up and you would knit them all together with the next st so they will look bunched up. Does that look like the picture?