An explosion is a rapid release of energy, and stronger explosions are often lethal to humans nearby as the energy destroys human tissue, leading to the creation of explosive weapons.
In the Battlefield series, explosions cause Splash Damage. Splash damage works by a projectile, whether it be a tank shell, grenade, C4, etc., hitting and exploding on a solid object radiating damage in a rippling fashion outwards to those nearby. The damage weakens the further the player is away from the initial area of impact up to the point where no damage is received leaving the player unharmed.
Explosions ignore hitbox and instead have damage modifiers based on the distance between the center of the explosion and the victim.