knit 3 stitches together
K3tog means knit 3 together, or simply knit 3 stitches together, and It’s a 2 stitch decrease.
Instead of going into our next knit stitch like we would normally we are going to insert our right needle into the 3rd stitch on our left needle, like this. We’re now going to insert our right needle, at the same time, into the two closer stitches, this can be a bit fiddly at first so take your time. Now work from here like you would a normal knit stitch, bringing the yarn around, picking up your new stitch and bringing it up and slipping the old stitches off your left needle.