The impact level is simply a reference to see how important that question is in the context of work environment.
For example, if the question "How much do you live with your boss?" (Green) comes out low has a moderate impact on the company. In other words, the world does not fall.
But, on the other hand if "My organization keeps me informed about important issues and changes." (Red) comes out low, this greatly affects the climate since people do not feel informed and taken into account.