Knitting abbreviation - YFON or YFRN

Knitting abbreviation YFON or YFRN stands for yarn forward and over needle or yarn over and round needle. It is used when switching from the knit stitch to the purl stitch with a yarn over in between.

Bring the yarn to the front, wrap the yarn around the right-hand needle with the yarn ending up back at the front of the work, ready to purl.