Work needed to rank

hello, I’m doing a bit of keyword research on kwfinder taking a look at the ranking difficult value (Also what do you think about it? It have some kind of value or not?) but I don’t really have an idea of how much work is needed to rank them… I mean someone can give me an idea of how much work is needed a kw with max 40?

I suppose that 0 to 10 its just page optimization right?

Thanks!