Mitten pattern help please

My first mitten pattern and I can’t figure it out. I am at the section where you put stitches aside for the thumb. This is sheep shop yarn company pattern #019. I have typed the words and punctuation exactly as they appear. I don’t think that this is correct but can’t find an errata. Can anyone translate this?

LEFT THUMB RIGHT THUMB
One needle 2: K1, K3 with 5" piece
One needle 3: K1, K3 with 5" of scrap yarn.
Slip 3 scrap yarn sts. Piece of scarp yarn. Slip 3
Back onto left needle and knit over scrap yarns sts.
Back onto left them. Continue in Stst until piece
needle and knit over them.
measures 3 1/4" from beginning of St.st. Continue
in Stst until piece section. Measures 3 1/4" from
beginning of St.st section.