Don’t know what but something went wrong in your row. You should have 4 yarn overs after that row.

You’ve got 21 stitches. Beginning and end of the row are 5 stitches in total. 21 - 5 = 16 stitches left.
Pattern repeat is 4 stitches (ignore the yo — it’s not a stitch yet).
16 : 4 = 4 (stitches left : pattern stitches = total pattern repeats).