This is a culinary/kitchen term. A stage, pronounced stah-ge. I think it is French, sounds funny. It basically means an unpaid worker who can be working for a day trying out at the restaurant, or a few weeks like an intern to learn. I staged at restaurants to learn and make connections. It gives you a more relaxed way to learn because you are not getting paid and you will not get yelled at for moving too slowly.
I have also staged at restaurants for jobs. It is like a trial for someone who wants to work at a restaurant because the team wants to see if you can hang. That’s what a stage is in the restaurant industry.
Just a Cook 