The guy will either be dead or he’ll be a war invalid for the rest of his life.
In both cases, he (or his family) will get a nice-looking medal and many teenies and armchair generals will bring up his name in online forums and on social media sites.
His comrades will probably all be okay. A single body can indeed effectively reduce a hand grenade’s damaging effects (explosive blast and fragments).
On the other hand, if their comrade hadn’t jumped on the grenade but had thrown his backpack or body armor over it instead, they would also have survived. Maybe not completely unharmed, but probably without any life-threatening injuries. Nobody becomes a war hero but everyone is alive.
The military teaches you many different ways how to deal with grenades landing in your position; throwing yourself over them is not one of them.
Roland Bartetzko is a former German Army, Croatian Defence Council, Kozovo Liberation Army