Be aware that vlookup without the fourth parameter (true or false) will default to "true" and will return an approximate match. Also the data table must be sorted ascending in column F, otherwise the results may be wrong. If you are after an exact match, you should use the "false" parameter.
That aside, you can compare the returned value with a 0, like
The Len() function is not required.
As an alternative to the double Vlookup, you can format the results with custom format
This will format positive and negative numbers with two decimals and display text, but no zero values. Adjust the number format to your needs.
In both cases, a zero value will be suppressed, even if it is the actual value in the lookup table.