Here are some examples of the VERT.ZOEKEN (vertical search) function in Excel.
As you can see this function also gives an output when certain valid but incorrect values are entered.
Input validation of the parameters before entering a value in a standard function
is therefore important. Otherwise the formula produces a seemingly normal output that is nonsense.
The use of the dollar sign '$' is used to select a fixed Cell.
This is handy when copying the formula to other cells, the fixed cell stays the same.
More information about cell selection can be found in the Exel Help and on the internet.