In a module the top grey line "applies to" is what your module is dimensioned by. Since your screenshot has white lines my guess is you are looking at what a specific line item is dimensioned buy. They can be different. Another way to see the list/dimensions is to leave blueprint mode and click on the pivot icon.
So a quick check on the dimensions of the module can be done from the modules tab in settings
Also you change dimensionality at module level from here directly
Inside the module , that is highlighted by grey , so this is applying to the module , ie default for all line items , however , you can change the dimensionality at line item level as shown(for subsidiary views purpose) .