Work both sides at once

On the neck of sweater (knit row) I knitted # of stitches as pattern said, bound off center # of stitches and knitted to end.

I am on Purl side and NOW pattern says "Work both sides at once, bind off 3 stitches at each neck edge once, bind off rem 3 each side.

Not sure what exactly to do.

YOUR ANSWER

Basically what your pattern is telling you to do is to knit both sides of the sweater at the same time on the same set of needles.

So you will need another ball of wool. Start knitting (purl stitches) on the right-hand side and knit across all stitches on that side.

Then you attached the new ball of wool to the stitches on the left-hand side of the piece and purl across those stitches.

You keep going in this manner, knitting the same row on both sides one after another, following the shaping instructions set out by your pattern until you complete the piece.