It is not really used snymore. It means not having any responsabilities ; carefree. It was isually only used as part of the phrase " footloose and fancy free"

Well young laidy FOOTLOOSE is an adjective and describes a person or people who can travel or do freely wherever or whatever they want maybe because of lacking or responsability or something like that. If you want a context there's a song and movie with the same name. I hope I've helped you. Se you soon.