What is Purl ridges?

I am new to knitting. I am working on a baby hat with simple knit and purl stiches. After I have completed the knit and purl stiches as stated it says to " 14 purl ridges on each side of work". I am not sure what that is? Thanks

Those are the ‘bumps’ When you can count 14 rows of the purl bumps on each side, then go to the next part.

Thanks!:yay: