Somebody 'well off', with enough means to provide for his/her own livelihood. Does't have to work for a living.
Not necessarily, the use of the word seems to vary from region to region. In Zeeland I encounter it often in lower-class people who do not yet, or do no longer work for a living. So, not because they do not have to, but because they are either too young (especially girls before marriage) or too old to work.