Help with knitting neck edge

Hi,

Please can someone help me understand this part of the pattern i am working on -

Work 3 rows dec 1 st at neck edge in every row. 21 sts.

It also asks me to turn my knitting before this (how do i do that?)

Thanks!

Continue working whatever pattern stitch you have been working and when you get to the neck edge (as opposed to the armhole edge) decrease 1 stitch. You can work a k2tog, ssk, p2tog or ssp or whatever decrease you prefer. The decreases are on 3 consecutive rows.
To turn your knitting, switch the needles in your hands as you would at the end of a row. You’ll be turning from the right side to the wrong side or from the wrong side to the right side.
Are you knitting in the round or back and forth?
What is the name of your pattern?