Grenade
There will always be other keywords to denote the type of explosive attack after rolling to hit. e.g. (Frag)
Grenades are thrown using using a Shoot action. Choose a target cube within range. If you do not have LOS to the target cube, then both the shooting model and the target cube must be visable when viewed directly above. (i.e The grenade is thrown directly into the cube if you have LOS, or lobbed over whatever is blocking LOS.)
Roll a 3 dice Ranged test (1) with no modifiers or rellows allowed. Success means that the Grenade has landed in the target cube. Failure requires a Scatter roll (see page 28 in the rulebook) to determine which cube the Grenade detonates in. The enemy does not make a roll to oppose this Shoot test, but there may be a later damage roll (e.g. Frag)
A Grenade that would Scatter through a solid wall (or the board edge) will bounce off it and stay in the original target cube.
The effect the Grenade has varies by type, see the weapon profile or item description for the Range, AP and Keywords for that grenade type.