Can anyone help me read this crochet pattern?

Hello

This is a pattern from a vintage pattern book and I need help reading this para for shaping sleeves:

Shoulder Shaping:
*Sl St Across first 10 (11, 12, 8, 9, 10) sts; work in sc across row to within last 10 (11, 12, 8,9,10) sts. Don not ch;...

turn. Rep from * once more. For men's sizes only: Sl st across first (7.8,9,) sts, work in sc across row to within last (7,8,9) sts. Fasten off.

I'm confused especialy with work in sc across row to witith last 10 (11, 12, 8,9,10) sts
What does within last mean here?

Can you please help? I'm crocheting this sweater as a birthday surprize gift for my husband and I have only 5 days to finish it

Hi,

sc means single crochet longstitch. sts means stitches.

So that sentence means work in the single crochet longstitch across the row to the last 10 stitches.

Good luck.