There are many different potential ways to write a formula using Index and
Match.
If you post the specific formula, it may help someone explain the usage
further.
Very briefly the syntax for Index is (Array,Row num, [Col num])
Thus Index(A1:A5,3) would return the value in A3 (the third postion in the
array)
If data cannot be sorted to allow a Lookup,Vlookup or Hloolup you may use a
Match function to get a position
A B
1 Apples 7
2 Pears 5
3 Grapes 3
4 Oranges 4
5 Pinapples 2
The function Index(B1:B5,Match("Pears",A1:A5,0)) would retun the value 5
Match ("Pears",A1:A5,0) finds the position of the first item in A1:A5 that
exactly equals (signified by the ,0) "Pears" in this case 2
The function is then reduced to Index(B1:B5,2) which returns the second item
in the array B1:B5 which is the number 5