What should I do if my waiting time between one flight to another is 15 hours?

Stroll everywhere and if your budget allows it, buy souvenirs, pizza 🍕 😋

Depending on your budget and amount of luggage, you can take an Uber and get to know Miami beach or wingood.

You can go out in the surroundings or go to see each floor of the airport, read or if you have online classes you can go forward. Or something that you want