Odd tags in vlookup advanced use - please help

I client came with some exercises she does not understand. She's an accounting student and her teacher is doing some complex use of the tool. The thing is that in vlookup (and hlookup) the guy uses some kind of labels/tags as fields. I have no idea how he created them, so I was wondering if anyone can help with it.
You can find the tags in the file "practico 10". The function is =VLOOKUP(E5;ORIGENSEGURO;HLOOKUP(F5;DESTINOSEGURO;2;FALSE);FALSE)*G5/100
VVTmYLi.png

Then this guy does another thing I have never seen: he adds numbers indicating columns number below the table and includes them in the VLOOKUP. I really don't understand what he's doing, though it does work. You can find the VLOOKUP function used in cell K3, sheet R2 of the file practico11.
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Links

I assume ORIGENSEGURO & DESTINOSEGURO are named ranges.

You can find it in "Formula" tab in the ribbon tool, Name Manager.

A complicated way to do a vlookup. It would have been easier to use INDEX/MATCH.