There is a formula in the law that specifies how much if your salary gets deducted every month based on specific criteria such as your marital status, your religion (yeah church taxes), whether it is your primary or secondary job etc.

That amount is calculated to be enough (a little bit to much in fact) to cover taxes for most people employed with a single job.

Unless you have extra income or deductions beyond a certain amount you don't have to file any tax return.

If you want to file one (pre filled with what they know) the government calculates what you need to pay/are owed and you have the right to dispute that.

You can use the free digitalised version of the former paper form or you can use a number of (often inexpensive) commercial programs