Apparently based on a game called OLAF, but has more recognizable traits of Sokoban, Fire is essentially a block pushing game where the object is to extinguish flames.

Throughout the various levels (there is more than forty in the game and apparently over a thousand in total, see the creator's website) there are small fires burning. Switching between use of the box and the ball, by pressing space, you are given the task of putting them out. The ball, however, is the only one of the pair capable of putting the fire out.

So, using skill, dexterity, logic and trial-and-error, work through the levels as they turn up and try to solve them without going psychotic. The game has been developed well and it looks great so there's really no reason not to try it.