As a sugar glider owner, you may occasionally hear people use the name "Joey" to refer to sugar gliders. The term "Joey" is basically just a descriptive term for a baby sugar glider. Generally one that's young enough to stay in the female's pouch.
A joey is just a term applied to a baby sugar glider. It doesn't in anyway indicate anything about the sex of the baby nor does it indicate any concerns or health problems. It's simply just a descriptive term that's used to refer to a baby or young sugar glider, generally one that's still within the pouch or not fully weaned from it's mother.
Most of the time it's not a term that you would experience because most sugar gliders are adopted or purchased after the age of weaning and they are no longer with their mother.
A lot of people will hear the term referred to when a breeder may say, "Oh, my female has four joeys." It's just a general term that is used in reference to a young sugar glider.