See this Mudcat thread for information about what nappy hair means:

thread.cfm?threadid=100728&messages=26
"Natty Dread"

Here is one post from that thread:

Subject: RE: Natty Dread (Bob Marley)
From: Azizi - PM
Date: 13 Apr 07 - 05:26 PM

"...from the TV coverage and photos that I have seen, none of these young women even have nappy hair. The closest is one who has corn rows (or something similar).'

KB, the texture of most Black people's hair is tightly curled {otherwise known as kinky and nappy}. This natural texture of the hair is 'masked' by straigtening the hair.

The hair is straightened by using a chemical perm {permanent} or by using a hot iron comb. In the olden days {up to the 1960s or so}, the method of heating the comb was by putting it in the fire on the kitchen stove. Nowadays, combs are heated by plugging them into an electric socket.

Once the naturally tightly curled hair is straightened, the hair is then curled and styled with a hot curling iron.

And that's the way it is...