If you routinely go to a yoga class every single Wednesday, you go weekly, or once every seven days. You might even refer to it as your weekly yoga class.
Anything that happens once a week is weekly, whether it's your weekly viewing of a TV show, your weekly algebra study group, or your family's weekly pizza night. At work you might get a weekly paycheck — or you might have a weekly job, watering your neighbors' plants and feeding their fish every Saturday morning. A magazine or newspaper that's published once a week is sometimes called a weekly, too.