The pattern says rib 3 on a buttonhole row(rib 2tog,yf,rib 8.What does this mean. Do l knit three stitches in rib...... Help
Yes, work the rib as it's been established.
So you'll work 3 in rib, then work 2 together in whichever stitch would have been next, yo, and rib the remaining stitches.
If you're working kpkpkp rib, you'd kpk,p2tog,yo,kpkpkpkp