Culture, among other things, is just a metric, like “weight”, “distance” or “personality”. It is a much more complex metric, because we are all part of it, regardless of whether we like it or not.
In a nut-shell, Culture allows us to understand the tendencies a group of humans have in comparison to other groups of humans, and it allows us to understand in a more precise manner, how the group will react to particular changes, to particular policies, or to particular outside threats (regardless if natural, or coming from other groups of humans).