The device can broadcast 5 different SSIDs and it is capable of roaming, i.e. seamlessly moving an end device from one AP to another (provided your end device is capable of this). This means that you are not stuck with your end device on the old AP when you move from one side of the flat to the other.
It is important to mention that you need to install a console for the Ubiquiti APs. The console is available as software or as hardware (e.g. Dream Machine, Cloud Key). The console is also useful in operation as it gives you deep insight into your network and performance.
Using mesh to connect one AP to another should always be second choice because you lose bandwidth. Check if you can pull a network cable instead so that both APs are on the cable.