It will look into the star forming regions in our own galaxy. It will also help to discover the structure of our galaxy. The galaxy is shaped like a disk, and we are located near the edge. This makes it difficult to determine the galaxy s structure, because dust clouds in the inner portions of the disk block our view. Since WIRE can see through those clouds, it will help determine galactic structure.
Brown dwarfs are relatively small objects that shine faintly, mostly in infrared light.
They do not shine for the same reasons that a normal star shines. A normal star shines because of energy supplied by nuclear fusion reactions in its central core. Brown dwarfs, at about 80 times as massive as Jupiter, still have too little mass to sustain nuclear fusion reactions in their cores. Instead, they glow dimly with the heat left over from their contraction. WIRE should be able to detect their feeble light up to about 35 light years away.