You basically take a dog into your home until it is adopted. This allows shelters to rescue more animals without having problems at their actual facility. It also allows the animals to have a better home than stuck in a shelter.

I would anticipate that they would not allow you to foster a dog as a first-time pet owner. There are many reasons for this. Some are as basic as the fact they can't be sure you'll take good care of the dog. Some are more complicated reasons, like many foster dogs are in need of some serious training and behavioral readjustment. Obviously that's beyond your capabilities at this time!!

If you're just looking for an animal "fix", I'd recommend volunteering at a shelter for now. You'll still make those animals' lives better, but it'll be easier on you and this crucial readjustment period of your life and will also prevent a dog being put in an unpleasant situation if your lifestyle doesn't work out for it