Hi and welcome to Knitting Help. Do exactly as it says:
k2tog, but don't slip the stitches off the needle, leave both stitches on the left needle and knit the first stitch then you will slip the stitches. after that, k1.
By slip the stitches I am assuming it means to move them off the left needle.
A link to your pattern would be helpful.
Cheating is an option. . . . Cheaters never win and winners never cheat, but smart knitters who want to retain an iota of sanity do, cheerfully. ~~Kory Stamper