Complex IF functions containing "ISNA" and "VLOOKUP"

I'm not new to excel, but I am fairly new to more complex formulas. I recently took a new job and, from what I hear, the guy I'm replacing was an excel wizard.

I know basic IF functions and simple VLOOKUP to replace values with text, but this is beyond me. Can someone translate each element of this formula into simple English and perhaps offer me a web resources for becoming more well versed in excel formulas?


Here's two examples of formulas he has in our master schedule that aren't working as expected and that I need to alter to get back on track:

=IF(ISBLANK(G2),"",IF(ISNA(VLOOKUP(A2,GE_CANCEL!A:B,1,FALSE)),"OPEN","CANCELLED"))

=IF(ISBLANK(N2),"",IF(ISNA(VLOOKUP(A2,GE_OPEN!A:C,3,FALSE)),O2,VLOOKUP(A2,GE_OPEN!A:C,3,FALSE)))