From the revenue generated you can deduct your business expenses, health care (around 250EUR base, can be 400, depends on your situation), pension expenses (if he wants to pay that) and than you have to pay income taxes.
Lets say he has 2500 EUR of pre-vat income after those expenses he would have to pay income taxes of roughly 500 EUR (32%) leaving 2000 EUR net income.
Yeah, it was just a snarky way of saying that you meant 'pre-tax', not 'pre-vat'. VAT (Value Added Tax) is a specific tax, one that only end-consumers pay.
Lets say he has 2500 EUR of pre-vat income after those expenses he would have to pay income taxes of roughly 500 EUR (32%) leaving 2000 EUR net income.