A router is an electrical device which, among other possibilities, makes it possible to connect to the internet. It is a device standing between your computer and the world wide web. If your ISP provides the router, it will most probably be configured and you won’t need to change anything. However, if you buy the router by yourself, you will need to configure it to match your ISP’s preferences. There are dozens of router manufacturers, and they have different ways of accessing the configuration panel of their routers. However, all of them use an IP address from the private block. The most popular router manufacturers are Cisco and Netgear, and they both use 192.168.1.1 as an accessing point. That means that you have to type that IP address into your browser, and you will access the configuration panel. Other manufacturers use IP addresses like 192.168.100.1 or 192.168.1.254. Some router producers use IPs like 192.168.0.1. However, all of them use a certain address from the 192.168 private block.
In order to make your router work, you will have to contact your ISP to get all the necessary data and configure your router properly. Your ISP has a website and there is probably a guide there on how to configure different types of routers in order to make them work. This may sound hard, but in reality it isn’t. You will just have to enter a few IP addresses from your ISP, tick a few boxes, maybe turn on wireless (if the router supports it), and you are ready to go.