If instructions say SK, it means Skip, whether that would be stitches or chains. If you are about to SK 2 (Skip 2) this means skip 2 stitches or 2 chains and do your required stitch into 3rd stitch.

When you come to the instructions saying do your stitch into the hole, it means that stitch or stitches needs to be done into the hole you made row before and not into the stitch or chain itself.