Welcome to KH!
(RS) cast off 6 stitches, k19, turn, leave rem sts on a holder.
This means to leave the sts that you haven't knit yet on a holder. They'll form the neck and second shoulder. You'll get to them later.
(RS) cast off rem 5 sts
At this point, you've finished the first shoulder and cut the yarn, leaving about a 6 inch tail to weave in later
[u]With RS facing, rejoin yarn to remaining stitches, cast off 14 sts, k to end.
OK, here is where you get to those sts that have been hanging out on the holder. You're going to put them back on a needle and with the RS facing, join a new end of yarn (leave about a 6 inch tail to weave in later), bind off the neck sts and then work on the second shoulder. Don't worry if the first stitch with the new end of yarn is a little loose. You can always go back and tighten it up later.