The serpentine belt came off all of the pulleys except one. It is the biggest pulley on the bottom left side.
A thrown belt is generally caused by either a seized peripheral - such as an alternator - AC compressor, or possibly a faulty tensioner or idler pulley. It is often suggested that if a belt has been thrown, that the belt be replaced, if all pulleys and peripherals check out fine. It is imperative that the belt be routed correctly, and installed properly, on each of the pulleys’ guide tracks. You may want to enlist the help of a mechanic, such as one from YourMechanic, who can inspect all of the pulleys and drive items, and who can also properly install a belt to prevent damage from the belt being thrown in the future.