Activate device Netflix what is it?

So, would like to know what it is and what it brings.

A Netflix account only supports a certain number of devices.
Otherwise you could e.g. Distribute to 20 people and all could look at the same account.

You can of course find further information on the homepage:

https://help.netflix.com/...e/node/283

Yes, but what do you do when activating the device?

That's why I sent the link.
A device has a hardware ID / model number etc.
This is registered under the respective account under Devices. Thus Netflix "knows" that this device belongs to the respective account.