It is a very thin phone that is flexible but still rigid. The images of it bending over online are a bit of an exaggeration. It is very light and very thin and it built with plastic substrates that are flexible. In other words, it is curved and rigid, but flexible (it’s hard to describe without having a play with it yourself). You cannot bend the camera, battery or the processors, so look upon it as a phone that is simply more durable (or less fragile) than other phones. And, a phone that has a bit of a curve to it.
The battery is placed within the curving flex phone by the use of stack and folding technology. It reduces the stress that is put on the battery when some fool tries to bend it or tries to stomp on it. It makes it harder to destroy the battery with bending forces.