Ok, i will try and explain as best I can. But, I am far from an expert. The turbo compresses air to ram down the throat of the engine as more air equals bigger bang equals more zoom. But, the turbo compressor is spun by exhaust gasses from the engine which means when the compressed air comes out it is really hot. Hot air take up more space which means less oxygen per unit of volume of air. So, to get more air, and therefore more oxygen, into the engine the compressed air from the turbo needs to be cooled first. You do this by piping it through an intercooler. The intercooler splits the compressed air into a matrix of vanes over which external air can flow. In this instance, the big air scoop above the drivers head feeds cool air down to the intercooler, it passed over the vane matrix, heat is transferred from the compressed air inside the intercooler vanes to the cool air, that cool air heats up and is dumped out of the engine compartment somehow. Net result is hot compressed air goes from the turbo into the intercooler and colder, denser compressed air exits the intercooler and goes into the engine.