@iamnotabot you should really try to research a little on your own before asking question like those on this forum. At least read the wikipedia article or something.
In this case the answer is also more or less roughly explained in the ZHA integration documentation introduction, and more information under sections about adding devices and limitations, see:
- https://www.home-assistant.io/integrations/zha#introduction
And - https://www.home-assistant.io/integrations/zha#using-router-devices-to-add-more-devices
And - https://www.home-assistant.io/integrations/zha#limitations
As well as - https://www.home-assistant.io/integrations/zha#zigbee-interference-avoidance-and-network-rangecoverage-optimization
So it is highly recommend that you read through all of the integration documentation regardless, read example this whole page:
But best is to do more research yourself yo learn more about any IoT protocols and standards, so suggest start by checking out the cookbook guide links: