When rolled up, the Girella is a small armchair described as being "ideal for the children's room." This seems accurate, as it's 70 cm high and 62 cm across, with a seat height of 41 cm (27.5 x 24 x 16 inches). So, probably not big enough for an adult but plenty big enough for kids of all ages. The fact that the seat is formed by the edges of the rolled-up mattress should make it more supportive.
When rolled out, the Girella is small single bed/play mattress measuring 193 x 80 cm (76 x 31.5 in), which is just a little smaller than a regular single bed. No mechanisms are involved at all, with the whole thing being made of soft materials: polyurethane foam with polyester padding and a lycra covering.
The Girella is priced at around US$700. Campeggi seems to specialize in kooky furniture, having previously turned heads at the Milan Design Fair in 2012.