Meaning of 8/2 for yarn description

What does 8/2 mean when describing a yarn for sale?

8 is the thread size, 2 is the ply. This is generally used for weaving but can be used for knitting and crocheting. carries it in 100% cotton and a cotton/linen blend from Valley Yarns.

Thank you Mary. I’m a new knitter and I’m often confused.
I’ve knitted a huge blanket with the knit stitch.
Next I knitted a twin sized blanket of squares of knit stitch and pearl stitch.
Now I’m trying a 2-color/2-ply College threow with a patterned letter “A”.
I am slow at learning.