Is that what he’s playing? Lol, I thought it was just a cool looking guitar!
The dobro has a wide shallow funnel shaped metal thing something like a pie plate, inside the body under the sounding hole, with half-a-dozen wire coils attached between the round grill on the top and the center of the piece below. It was a way, before the advent of electric guitars, to make a twangier sound. The neck is usually wider and flat, so that it can be used with a finger slide—again, man-made special effects before electrification.
The dobro is often hung around the neck with a longer strap so it can be held flat to be played “slide”.
Bluegrass wouldn’t be bluegrass without the dobro!