SSK (Slip-slip-Knit) is a simple decrease, meaning you remove 1 stitch from your stitches count. It leans toward the left.
Work according to pattern until you need to make an SSK decrease.
Slip the 1st stitch from left needle to right needle knitwise.
Slip a 2nd sticth from left needle to right needle knitwise.
Pass the tip of left needle into the 2 slipped stitches from left to right.
Pass the working yarn arount the tip of the right needle and pull the new stitche from the 2 slipped stitches.