So, I am taking an advanced Office course in college. We are currently working in Excel.
I missed a submission on the online homework site, yet my formula seemed correct and yielded the appropriate result.
I asked my instructor what was wrong with my formula and he told me to use the "@" symbol and learn what it does...
So far, I do not know what it does and Google is yielding literally no results (not to mention our course book doesn't mention it).

Background info on homework:
I was working in data tables and structured formulas. The formula I was using was VLOOKUP.
For some reason, when I referenced the table as =VLOOKUP(Table[Column_Name....]) it yielded the right result. But I had to put =VLOOKUP(Table[@[Column_Name...]]).

So, what is the difference between using the "@" symbol and not using it?
Under what circumstances would you use one or the other?

Thanks for taking the time!