train cabins

For booking reservations, the best is to use this guide:

https://www.seat61.com/interrail-and-eurail-reservations.htm

If that doesn't work for you, then please mention route, date and departure time.

About which train journey/route are you talking?

“is a possibility to book train cabin” - yes for many trains, no for some trains.

“How much does it cost for 5 people” - it depends on many things, primarily the carrier.  Some reservations are under €10, some are over €30.  Some are per trip (so multiple trains are charged multiple times), some are charged by booking (so Warsaw-Berlin-Vienna might still only be a few €)

As above, if you give an indication of your route people will be able to help more.

I'm talking about the train from Bratislava to Berlin and the train form Berlin to Warsaw 

Which train there are multiple between these Bratislava and Berlin during the day. And one direct night train.

Reservations on the train from Berlin - Warsaw are 4€/person (if bought from the polish railway) 

I'm talking about a cabin for the night train. I would also wanted to know if I book the cabins through the app.

The night train can be reserved through ÖBB check the guide out for how to do it. Its has dynamic prices for the reservation depending on demand.

That's why we ask route, date and departure time. That defines the train and then people can check.

Please use the Seat61 reservation page to see how and where you can book. If that does not work, then please mention route, date and departure time (yes, all of them!) when that does not work for you.