The result is a variant array -- one index to the array for every column specified in the KeyValues parameter:

procedure TForm .Button Click(Sender: TObject);
var
  MyResults: Variant;
  MyKeyFields, MyKeyValues: String;
  MySearchForValue: Integer;
begin
  MyKeyFields := 'CustNo';
  MySearchForValue :=  35 ;
  MyReturnColumns := 'Company;Addr ';
  MyResults := Table .Lookup(MyKeyFields, MySearchForValue, 
                            MyKeyValues);
    if not VarIsNull(MyResults) then
      ShowMessage('Company: ' + MyResults[0] + '   Address: ' + 
                MyResults[ ]);
  {  With DBDemos data this returns
    "Company: Sight Diver   Address:   Neptune Lane" }
end;