Understanding your business costs - to make more profit

Well “duh”, I can hear some of you sigh, “I know costs impact profit, so of course understanding them makes you more profitable”. Who TF is this Davina person and what on earth does she think they can teach me if they are stating this obvious sh*t. Firstly, it's Davinia (can you spot the difference?) And secondly - well, fair one. Because yes, you are correct: costs do directly impact profit because income minus costs = profit But knowing costs and understanding costs are two