It is a single room with a mini kitchen and bathroom inside. You get everything you need in the kitchen. The room has a small balcony, which is really nice. The place is very clean. We got a nice experience because we could check in the morning at 7 or 8 am, after an overnight journey with the bus to reach Prague. The initial check-in is 3 pm, but we asked the host if we could check in earlier. And yes, we could.
The apartment is a bit far from the city center (15-20 minutes with tram), but the public transport is really near (Tram 2-3 minutes walking and metro 8-10 minutes walking).
In the end, what I found so cool, the host provides free locker, so you can put your belongings there, on the check out day. So you don't have to carry heavy things or pay for a locker. And you can take it anytime. Our case, we went back at 9 pm to take our belongings.
This apartment is very recommended :)