slip 1 stitch with yarn in front
Sl1wyif is means, slip 1 stitch with your yarn in front.
To work this stitch, let’s imagine a pattern is asking you to knit, then slip 1 with yarn in front and then knit another stitch.
Knit 1 stitch, now bring your working yarn through your 2 knitting needle tips so that it’s in front of your work now. Insert your right needle tip into your next stitch on your left needle from right to left and slip this stitch.
You can now knit the next stitch, by bringing the yarn to the back side of your work again.