Help reading For loop with range variable

Hi Guys,

I'm trying to understand a code from work and I can't get it. I copied only a part of the code here so please don't run it. Also, I have manual inputs in columns L and M (nodes labels such as 1, 2 and 2,3) and section labels on column N (such as BarFT3, BarFT4 etc):

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What is this loop doing? I just get the first For loop: goes through every lable on colum N (from 1 to ne) but then what?
What is happening to range nudo(n,j)? How works this ">" sign between nudo(n.j) and nn?

Thanks guys