. . .Where science gives us a way to understand how the mental mechanisms we rely on in our daily and professional lives are made possible by brain functionalities, philosophy offers a way to understand how our intellect, our grasp of things, works in us. That is, an account of those features or elements in our mental lives (what goes on in us when we think about and understand things) which make up our grasp of the world around us (our subjective placement in the objective world we recognize as our milieu) requires a conceptual inquiry more suited to philosophy than science. Of course, the two cannot be divorced because science surely requires conceptual clarity in the formulation of its hypotheses and theories while philosophy depends on agreement with the best available empirical knowledge (scientific information) if it's to provide viable conceptual accounts.
If science can tell us what brains have to do to generate the elements we experience in our mental lives, and how our brains got that way, philosophy is needed to understand what the mental features caused by our brains' being "that way" actually consists of. That is, we need to know what's going on with us when we conceptualize the world around us in terms of spatial and temporal pictures and plan our actions, within that layered context, and evaluate the possibilities accordingly. Only with that sort of account can we know just what it is the brain's structure and functional behaviors make possible.