In symmetry group theory, what makes 2 rotational axes perpendicular?

Question

I'm trying to determine the symmetry of molecules and after finding all symmetry elements I need to follow a flowchart to determine what point group it belongs to. At one point in the flowchart, the following question is asked:

"Select $C_n$ with the highest $n$; then, is $nC_2$ perpendicular to $C_n$?"

What is meant by this?
In the example I'm trying to solve $n = 2$, I've tried comparing the molecule when rotated according to $C_n = C_2$ with the molecule when rotated $n=2$ times according to $C_2$, as the above sentence states, I don't see how I can determine if this is perpendicular or not.

Answer 1

I think I just realised what the flowchart asks, a better way to formulate it would be:

"Select $C_n$ with the highest $n$; then, are there $n$ $C_2$'s perpendicular to $C_n$"

Is this correct?