Hey Stefano,
see here for the duty of AC and DC reactors. See also Difference between AC reactor and DC reactor
Here you can see from a diagram from Omron MX2 VFD Manual (en) (version française ici) that there are some optional components you can use with your VFD (mainly applies to other manufacturers as well):
What these components do is described in the table. As you can see, for beginning, a circuit breaker is all you need. And a spindle of course ![]()
Next thing most operators would look at would be a brake resistor and the EMI input filter. The first allows faster decreasing spindle speed and the latter reduces high-frequency electromagnetic noise effects on your power wiring.

