The IKEA pull-out bed is intended to be a sofa during the day.
The second twin-bed can be pulled-out for the night.
To pull the second twin-bed out, grab the front panel of the bed and gently pull it out. The best is to do that with two people, one on each end of the front panel. Once pulled out, slide the second mattress on it.
Note: Before pulling out the second bed move the folding table.