The output format for the numbers can be determined in the list in the Format column. Click on  Suggestions to see suggested values.

Example:
###.##0,00 €;-###.##0,00 €;

Results:
12.581,35 €; - 125,00; 

The hash is used as a placeholder (dot and comma divide into thousands and decimal places). The semicolon (;) separates several formatting variants. In the example shown above, the first formatting stands for a positive amount, the second formatting for a negative amount and the third formatting gives no result if no amount is given.