Lookup up cell values in Numbers
This answer to a related question explains how to use VLOOKUP in combination with IFERROR.

If VLOOKUP cannot find the exact match, then it throws an error.  To catch this error, wrapping the formula in the IFERROR function allows the author to supply a default (in the OP's case, an empty string "") to display in the event of no match.

The following example uses a third table to display the translation.  That table is then locked so as to protect the formula from being inadvertently overwritten.  The words NOT FOUND are used here to show the error event.

If match is found:



No match:



From the documentation:  


  VLOOKUP(search-for, columns-range, return-column, close-match)
  
  search-for: The value to find. search-value can contain any value.
  
  columns-range: A collection of cells. columns-range must contain a
  reference to a single range of cells, which may contain any values.
  
  return-column: A number value that specifies the relative column
  number of the cell from which to return the value. The leftmost column
  in the collection is column 1.
  
  close-match: An optional modal value that determines whether an exact
  match is required.
  
  close match (TRUE, 1, or omitted): If there’s no exact match, select
  the row with the largest left-column value that is less than or equal
  to the search value. If you use close match, you can’t use wildcards
  in search-for.
  
  exact match (FALSE or 0): If there’s no exact match, returns an error.
  If you use exact match, you can use wildcards in search-for. You can
  use the wildcard ? (question mark) to represent one character, an *
  (asterisk) to represent multiple characters, and a ~ (tilde) to
  specify that the following character should be matched rather than
  used as a wildcard.