If you have Excel 2013+ and want to specifically target #N/A errors then you can use the IFNA() function.
=IFNA(VLOOKUP(Lookup_Value,Table_array,Col_index_num,Range_lookup),"")
If you have Excel 2007+ and want to target all errors you can use IFERROR().
=IFERROR(VLOOKUP(Lookup_Value,Table_array,Col_index_num,Range_lookup),"")
If you have earlier versions then you have to use a combination of IF() and either ISNA() or ISERROR().
=IF(ISERROR(VLOOKUP(Lookup_Value,Table_array,Col_index_num,Range_lookup)),"",VLOOKUP(Lookup_Value,Table_array,Col_index_num,Range_lookup))