From what we see here, it looks like Timothee Chalamet is about to fall off of this Dune vehicle, known as an ornithopter. Lucky for him, Josh Brolin’s character is there to protect him, and save him from tumbling into whatever waits in those hot sands. And there’s a pretty specific reason why this is even happening in the first place.
Article source: https://www.cinemablend.com/news/2496020/dunes-awesome-new-photo-puts-josh-brolin-and-timothee-chalamet-in-the-desert