ok so population generates your raw production
theres a curve formula posted somewhere so its not a straight 1:1 ratio
raw production is then modified by any production modifiers to give you your total value of production
the big problem here is that there is no way to check production ATM no tooltips no nothing.
ok so once you have your total production points that gets split up by the economic wheel (the orange, green, and blue circle in the govern screen)
this gives you raw numbers of research, manufacturing and wealth which then get afffected by your respective modifiers to give you your final values.
so short answer 10% production is like a 10% boost to whatever your planet is doing