Firstly, CYBIT is one of the defines among others which is used to support type modifiers for cross platforms IDE's like Keil. CYBIT maps to bit data type in Keil and uint8 in other platforms. You can find information on these in page number 8 under the section "Keil 8051 Compatibility Defines" (Link: http://www.cypress.com/file/130561/download )
Secondly, you can right click on Check_Mode and select "Find all active references". Then you will be shown the places where the variable is being used and hence obtain the value of it. I could help you more if you could attach your project.