It refers to the second column of the range used in the Vlookup
formula. In this case you are only using $A$66:$B$70, but if this was a
table of, say, 5 columns then your range would be $A$66:$E$70, and the
"2" could be 3, 4 or 5 to return data from the appropriate column.

The FALSE argument (could be 0 instead) means you are only interested
in an exact match.

Hope this helps.

Pete