It means you have a bird with Yellow Legs and Darkening genes which = green/willowWhat do green legs mean???
White legs are dominant over yellow: So your bird has recessive yellow skin with genes that darken the legs, if your bird had the white gene plus the darkening gene it would have slate legs.
https://www.backyardchickens.com/t/242730/chick-chicken-leg-color
https://www.backyardchickens.com/t/472912/leg-color-genetics
There is some sex linking invoved when pure leg colors are crossed... in theory if you where 100% about a roo's genetics and a hens and you used the right combo you could tell the sex based on leg color.
Means zip as far as egg color though. I hope the threads help explain better.