Why do you want to purchase it before you know what it does?

It's an entry-level WiFi router with UniFi's Network software, which provides the ability to buy more UniFi gear (switches and additional APs) if you have a really big house and/or wish to connect more than 1 device over ethernet. Unlike its bigger siblings, the Dream Router and the Dream Machine, it lacks additional built-in ethernet ports (i.e. you'd need to buy a switch) and can't host security cameras (the UniFi Protect product line).

Pretty good summary, though I'd add that it's also (probably) more stable than a lot of common home routers.