Some WiFi repeaters have 1 or more network connection you can connect a network device with a network cable to. The WiFi signal is converted into wired internet, so that you can also use internet via cable at any desired place in the house, in addition to the repeater function. This way, you can also connect a device without WiFi to the internet without having to pull cables. Keep in mind that this doesn't make the connection more stable, because the network connection to your router is still wireless.