I need batter understanding on check box please

Hi,
Im little confused of the output a checkbox should return. If someone can explain to me I would be very grateful. Im using this in Elementor so I can get class for certain fields to get toggle on visibility.

In choice field I have:
PC
Console
Mobile

and according to the field hint below for batter control I can use:
pcCSS : PC
consoleCSS : Console
mobileCSS : Mobile

From what I understand this is value : label, correct?
But how come regardless of what I choose in Return Value I always get the Label?

tnx