Hello,

A typical VLOOKUP will look like this
=VLOOKUP(Lookup_Value, Table_Array, Column_No, [Not_exact_match])
What it does is "Vertically lookup" your Lookup_Value in the column number Column_No, and return exact match or approximate match (basing on Lookup_Type, if omitted it will be "True" by default, meaning approximate looking).
In your formula, however, you use MATCH to find the Column_No, thus you have another formula, hence it may have a different range to lookup for value. MATCH function was used to find the column where your value can be in, then return the distance from whichever column it starts (for example, if it starts at column A, and found it at C, it will return 3; if it starts at D, and found it at F, it will still return 3).

Hope this help.