Thanks for visiting and questioning,
1 X 1 rib (ribbing) means a repetition or k1,p1 or p1,k1.
You do this by k1, p1 (or p1 k1 whichever the direction gives) and then repeat k1, p1 over and over until the end of the row. Ribbing is stretchy. It's preferable for the sweater's cuffs and border or neckline.
Retro stitch is a name given to a knitting pattern, probably the one from the past. Multiple of 8 sts + 6 means you need to have 8 sts plus 6 more sts to make this pattern. You need to subtract 8 sts when you want to narrow the pattern and add 8 sts to widen the pattern.
I hope this makes sense.
Have fun knitting!
Ratcha