This sign means "light" as in "doesn't weigh very much.
I also use it to mean "light" as in "light blue" or "light yellow."
When discussing colors you can often express the concept of "light"
by doing the signs with a smaller, more delicate movement, with a
bit of an "ooh" facial expression. Another way is by signing the
"little bit" sign (the version of "little bit" that flicks the thumb
out twice from the bent index finger).
You can learn
American Sign Language (ASL) online at American Sign Language University ™
ASL resources by Lifeprint.com © Dr. William Vicars