This stitch is used for joining together stitches that are on two separate knitting needles. It is similar to a 3-needle bind off.
I’ve included two variations: k2tog-fb, where you simply knit together one stitch from the front needle, and one stitch from the back needle. As well as k2tog-f&b, where you k2tog two stitches from the front needle, plus k2tog two stitches from the back needle, plus knitting together those two k2togs.
Insert right needle into first stitch on front needle as if to knit and first stitch on back needle as to knit and knit them together.
Go into 2 front ndl sts as to k2tog then go into 2 back ndl sts as to k2tog and k2tog-fb. 2 sts off each ndl become 1 st. (-3 sts)