Deutsche Bahn tickets only feature the details of the primary passenger. It is thus completely normal for there to be only one name printed on the ticket.
The total number of passengers is shown in German, in the top right hand corner of the ticket. 'Erwachsene’ or ‘Erw’ indicates the number of adults and ‘Kinder’ indicates the number of children.
Passengers under six years old will not be listed on the ticket but are still eligible to travel.